ACT Top 100 Vocabulary Words
The 100 most important words commonly appearing in ACT Reading passages. Learn definitions, see them in context, and study the full word family for each entry.
100 words · Part of speech · Definition · Example · Word family
How ACT tests vocabulary: Unlike the SAT, the ACT does not have dedicated vocabulary questions. Instead, vocabulary knowledge is tested indirectly through Reading comprehension. Understanding the precise meaning of words helps you distinguish between similar answer choices, especially in tone and purpose questions.
| # | Word | Part of Speech | Definition | Example Sentence | Word Family |
|---|---|---|---|---|---|
| 1 | abstract | adjective/noun | Existing in thought or as an idea rather than as a concrete object; a summary. | The passage explores the abstract concept of justice as it applies to modern legal systems. | abstract / abstraction / abstractly / abstractness |
| 2 | adversary | noun | One's opponent in a contest, conflict, or dispute; an enemy. | The two scientists, once adversaries, eventually collaborated on the same research project. | adversary / adversarial / adversarially |
| 3 | advocate | noun/verb | A person who supports a cause; to publicly recommend or support. | Environmental advocates lobbied Congress to strengthen emissions standards. | advocate / advocacy / advocating / advocated |
| 4 | affluent | adjective | Having a great deal of money; wealthy; prosperous. | Students from affluent backgrounds tend to have greater access to academic resources. | affluent / affluence / affluently |
| 5 | alleviate | verb | To make suffering, deficiency, or a problem less severe. | New infrastructure projects were designed to alleviate traffic congestion in the city center. | alleviate / alleviation / alleviative |
| 6 | altruistic | adjective | Showing a disinterested and selfless concern for the well-being of others. | The passage questions whether apparently altruistic behavior can ever be entirely selfless. | altruistic / altruism / altruist / altruistically |
| 7 | ambivalent | adjective | Having mixed feelings or contradictory ideas about something or someone. | The author is ambivalent about technology, celebrating its benefits while mourning its costs. | ambivalent / ambivalence / ambivalently |
| 8 | analogous | adjective | Comparable in certain respects; similar in function but not in origin. | The article argues that the brain's memory systems are analogous to a computer's storage architecture. | analogous / analogy / analogously / analogize |
| 9 | antagonist | noun | A person who actively opposes or is hostile to someone; an adversary. | In the passage, the antagonist's role is to challenge the protagonist's assumptions about progress. | antagonist / antagonism / antagonistic / antagonize |
| 10 | apathetic | adjective | Showing or feeling no interest, enthusiasm, or concern. | Voter apathy among younger generations is a recurring theme in the political science literature. | apathetic / apathy / apathetically |
| 11 | arbitrary | adjective | Based on random choice or personal whim rather than any reason or system. | Critics argued that the new classification system was arbitrary and scientifically unjustified. | arbitrary / arbitrarily / arbitrariness / arbitrate |
| 12 | archaic | adjective | Very old or old-fashioned; no longer in current use. | The passage contrasts archaic land management practices with modern precision agriculture. | archaic / archaism / archaically |
| 13 | assert | verb | To state a fact or belief confidently and forcefully. | The author asserts that economic inequality is the primary driver of social instability. | assert / assertion / assertive / assertively |
| 14 | bias | noun/verb | Prejudice in favor of or against a person or group; to cause to feel such prejudice. | Confirmation bias leads researchers to favor evidence that supports their existing hypotheses. | bias / biased / unbiased / biasedly |
| 15 | catalyst | noun | A substance that increases the rate of a chemical reaction; a person or event that causes change. | The publication of the controversial study served as a catalyst for a complete revision of the field's assumptions. | catalyst / catalyze / catalytic / catalytically |
| 16 | chronological | adjective | Relating to the arrangement of events in the order they occurred in time. | The autobiography is not structured chronologically but moves freely between time periods. | chronological / chronology / chronologically / anachronism |
| 17 | collaborate | verb | To work jointly with others toward a common goal. | The research team collaborated with universities in four countries to gather comparative data. | collaborate / collaboration / collaborative / collaboratively |
| 18 | compel | verb | To force or drive; to strongly motivate someone to do something. | The weight of evidence compelled the committee to revise its earlier recommendations. | compel / compulsion / compelling / compellingly |
| 19 | comprehensive | adjective | Complete; including all or nearly all elements; thorough. | The study provided the most comprehensive analysis of ocean acidification published to date. | comprehensive / comprehensively / comprehensiveness / comprehend |
| 20 | concede | verb | To admit that something is true; to surrender or give up. | Even critics of the theory concede that it explains some observations better than the alternative. | concede / concession / concessive / concedingly |
| 21 | condescending | adjective | Showing a superior attitude; treating others as if they are less important. | The reviewer's condescending tone alienated readers who might otherwise have agreed with the argument. | condescending / condescendingly / condescension |
| 22 | contempt | noun | The feeling that a person or thing is worthless or beneath consideration. | The passage reveals the author's barely concealed contempt for the policies of the previous administration. | contempt / contemptuous / contemptuously / contemptible |
| 23 | contemporary | adjective | Belonging to the same time period; modern and current. | Contemporary research challenges many assumptions that were considered settled in the 1990s. | contemporary / contemporaneous / contemporaneously |
| 24 | contradict | verb | To deny the truth of; to be in conflict with. | The new findings directly contradict the conclusions of the landmark 2010 study. | contradict / contradiction / contradictory / contradictorily |
| 25 | controversial | adjective | Giving rise to or likely to give rise to public disagreement. | The author deliberately chose a controversial title to attract wider attention to her argument. | controversial / controversy / controversially / uncontroversial |
| 26 | conventional | adjective | Based on what is generally done or believed; traditional and ordinary. | The experiment challenged conventional wisdom about the relationship between stress and productivity. | conventional / convention / conventionally / unconventional |
| 27 | counterintuitive | adjective | Contrary to intuition or common-sense expectation. | The passage presents the counterintuitive finding that more choice can lead to less satisfaction. | counterintuitive / counterintuitively / intuitive / intuition |
| 28 | credibility | noun | The quality of being trusted and believed in; trustworthiness. | The researcher's credibility was undermined by her failure to disclose potential conflicts of interest. | credibility / credible / credibly / incredible |
| 29 | critique | noun/verb | A detailed analysis and assessment; to analyze and comment on something. | The article offers a thoughtful critique of current urban planning models. | critique / criticism / critic / critical / critically |
| 30 | crucial | adjective | Decisively important; critical to the outcome. | Access to education is crucial for breaking cycles of intergenerational poverty. | crucial / crucially |
| 31 | cynicism | noun | An inclination to believe that people are motivated purely by self-interest. | Public cynicism toward institutions has grown significantly over the past two decades. | cynicism / cynical / cynic / cynically |
| 32 | decipher | verb | To convert a coded message into intelligible language; to understand something obscure. | Archaeologists spent decades attempting to decipher the ancient script found at the excavation site. | decipher / decipherable / undecipherable |
| 33 | deduce | verb | To arrive at a conclusion by reasoning; to draw a logical inference. | From the available evidence, the investigator deduced that the fire had been deliberately set. | deduce / deduction / deductive / deductively |
| 34 | deficiency | noun | A lack or shortage; a failing or shortcoming. | A deficiency in vitamin D has been linked to increased risk of bone fractures and immune dysfunction. | deficiency / deficient / deficiently / deficit |
| 35 | deliberate | adjective/verb | Done consciously and intentionally; to think carefully before deciding. | The organization made a deliberate decision to prioritize long-term sustainability over short-term profits. | deliberate / deliberately / deliberation / deliberative |
| 36 | detrimental | adjective | Tending to cause harm; damaging. | The study found that excessive screen time was detrimental to sleep quality in adolescents. | detrimental / detrimentally / detriment |
| 37 | discourse | noun | Written or spoken communication; formal discussion of a topic. | Public discourse on climate change has become increasingly polarized in recent years. | discourse / discursive / discursively |
| 38 | dispel | verb | To make a doubt, feeling, or belief disappear; to scatter. | The researchers sought to dispel the widespread myth that vaccines cause autism. | dispel / dispelled / dispelling |
| 39 | disseminate | verb | To spread information, knowledge, or ideas widely. | Scientific journals exist to disseminate research findings to the broader community. | disseminate / dissemination / disseminative |
| 40 | dominant | adjective | Most important, powerful, or influential; most prevalent. | English has become the dominant language of international scientific communication. | dominant / dominance / dominate / domination |
| 41 | elicit | verb | To evoke or draw out a response, answer, or reaction. | The survey was designed to elicit honest responses about workplace conditions. | elicit / elicitation / elicited / eliciting |
| 42 | empathy | noun | The ability to understand and share the feelings of another. | The passage argues that literature cultivates empathy by allowing readers to inhabit other perspectives. | empathy / empathetic / empathize / empathetically |
| 43 | endorse | verb | To declare one's public approval of; to support or recommend. | The medical association refused to endorse the treatment until controlled trials were completed. | endorse / endorsement / endorsed / endorsing |
| 44 | erode | verb | To gradually wear away; to gradually destroy or weaken. | Public trust in science tends to erode when researchers fail to communicate uncertainty clearly. | erode / erosion / eroding / eroded |
| 45 | evolve | verb | To develop gradually over generations or over time. | Our understanding of the human genome has evolved rapidly since the completion of the Human Genome Project. | evolve / evolution / evolutionary / evolutionarily |
| 46 | exemplify | verb | To be a typical example of; to illustrate by giving an example. | The case study exemplifies the broader trend toward community-based conservation models. | exemplify / example / exemplification / exemplary |
| 47 | exploit | verb/noun | To make full use of, often unfairly; a bold or brilliant achievement. | Industrial nations have historically exploited the natural resources of less developed regions. | exploit / exploitation / exploitative / exploiter |
| 48 | fundamental | adjective | Forming a necessary base or core; of central importance. | Literacy is a fundamental skill on which all other learning depends. | fundamental / fundamentally / fundamentalism / fundamentals |
| 49 | generalize | verb | To make a general or broad statement based on specific examples. | The author is careful not to generalize from a single case study to the entire population. | generalize / generalization / general / generally |
| 50 | hierarchy | noun | A system in which members are ranked according to status or authority. | The passage examines how power hierarchies within organizations shape decision-making processes. | hierarchy / hierarchical / hierarchically / hierarchize |
| 51 | idealize | verb | To regard or represent as perfect or better than in reality. | The memoir tends to idealize the author's childhood, glossing over the difficulties she faced. | idealize / idealization / ideal / idealized / idealism |
| 52 | imply | verb | To suggest something without stating it explicitly. | The author does not state her conclusion outright but implies it through carefully chosen examples. | imply / implication / implied / implicit |
| 53 | inevitable | adjective | Certain to happen; unavoidable. | The passage presents urbanization as an inevitable consequence of industrial development. | inevitable / inevitably / inevitability / avoidable |
| 54 | inference | noun | A conclusion reached by reasoning from evidence; a deduction. | The inference drawn from the data is that the two populations share a common ancestor. | inference / infer / inferable / inferential |
| 55 | intrinsic | adjective | Belonging naturally; essential; not depending on external factors. | The philosopher argues that human dignity has intrinsic value, independent of social recognition. | intrinsic / intrinsically / extrinsic |
| 56 | ironic | adjective | Happening in the opposite way to what is expected; using irony. | It is ironic that the development intended to preserve green space led to the destruction of a wetland. | ironic / ironically / irony / ironist |
| 57 | juxtapose | verb | To place or deal with close together for contrasting effect. | The author juxtaposes images of wealth and poverty to underscore the extent of economic inequality. | juxtapose / juxtaposition / juxtaposed |
| 58 | lament | verb/noun | To express passionate grief about something; a passionate expression of grief. | The essayist laments the loss of long-form journalism in the age of social media. | lament / lamentation / lamentable / lamentably |
| 59 | legitimate | adjective | Conforming to the law; rightful; genuine. | The author raises legitimate questions about the scientific validity of the study. | legitimate / legitimacy / legitimately / illegitimate |
| 60 | literal | adjective | Taking words in their usual or primary sense; not figurative. | The phrase should be understood in its literal sense, not as a metaphor. | literal / literally / literalism / figurative |
| 61 | manipulate | verb | To handle or control in a skillful manner; to influence in a clever or unscrupulous way. | The study examined how advertisers manipulate visual cues to influence consumer purchasing decisions. | manipulate / manipulation / manipulative / manipulator |
| 62 | metaphor | noun | A figure of speech in which a word or phrase is applied to something it does not literally denote. | The author uses the metaphor of a rising tide to describe the gradual spread of automation. | metaphor / metaphorical / metaphorically / metaphorize |
| 63 | methodical | adjective | Done according to a systematic or established method; orderly. | The researcher's methodical approach to data collection left no room for ambiguity. | methodical / methodically / method / methodology |
| 64 | meticulous | adjective | Showing great attention to detail; very careful and precise. | The meticulous restoration of the painting took more than two years to complete. | meticulous / meticulously / meticulousness |
| 65 | objective | adjective | Not influenced by personal feelings or opinions; impartial. | The panel sought an objective assessment of the competing policy proposals. | objective / objectivity / objectively / subjective |
| 66 | obscure | adjective/verb | Not discovered or known; unclear; to conceal or make unclear. | Technical jargon can obscure meaning and prevent important ideas from reaching a general audience. | obscure / obscurity / obscurely / obscuration |
| 67 | orthodox | adjective | Conforming to what is generally or traditionally accepted; conventional. | The author's interpretation departs sharply from the orthodox view of the historical event. | orthodox / orthodoxy / orthodox / unorthodox |
| 68 | paradox | noun | A seemingly contradictory statement that may nonetheless be true. | The paradox of choice suggests that having more options can reduce overall satisfaction. | paradox / paradoxical / paradoxically |
| 69 | perpetuate | verb | To make something continue indefinitely; to preserve from oblivion. | The passage argues that standardized testing perpetuates existing educational inequalities. | perpetuate / perpetuation / perpetually / perpetual |
| 70 | persevere | verb | To continue steadfastly despite difficulty or discouragement. | The researchers persevered through multiple failed experiments before finally isolating the compound. | persevere / perseverance / perseverant / persisting |
| 71 | perspective | noun | A particular way of thinking about something; a point of view. | The memoir offers a unique perspective on the civil rights movement from within the community. | perspective / perspectival / perspectively |
| 72 | phenomena | noun | Plural of phenomenon: observable facts or events; remarkable things. | The text describes two seemingly unrelated phenomena that share a common underlying cause. | phenomena / phenomenon / phenomenal / phenomenally |
| 73 | plausible | adjective | Seeming reasonable or probable; appearing to be valid or acceptable. | The most plausible interpretation of the data is that the effect diminishes over time. | plausible / plausibility / plausibly / implausible |
| 74 | pragmatic | adjective | Dealing with things sensibly and realistically rather than theoretically. | The author advocates a pragmatic approach: implement what works rather than what theory predicts. | pragmatic / pragmatism / pragmatist / pragmatically |
| 75 | prevalent | adjective | Widespread; commonly occurring; dominant. | Misinformation about vaccines has become increasingly prevalent on social media platforms. | prevalent / prevalence / prevalently |
| 76 | proponent | noun | A person who advocates a theory, proposal, or course of action. | Proponents of renewable energy argue that the economic benefits now outweigh the initial costs. | proponent / proponents / propose / proposition |
| 77 | prosper | verb | To succeed in material terms; to flourish; to thrive. | Communities that invest in early childhood education tend to prosper economically in the long run. | prosper / prosperity / prosperous / prosperously |
| 78 | qualify | verb | To make less absolute; to add restrictions or conditions to a claim. | The author carefully qualifies her claims, acknowledging the limitations of the available evidence. | qualify / qualification / qualified / qualifier |
| 79 | radical | adjective | Relating to fundamental change; departing markedly from the usual. | The proposal was considered too radical by the committee, which opted for incremental reform. | radical / radically / radicalism / radicalize |
| 80 | refute | verb | To prove a statement or person to be wrong; to disprove. | The author attempts to refute three common objections to the theory in the final section. | refute / refutation / refutable / irrefutable |
| 81 | relentless | adjective | Unceasingly intense; harsh or inflexible; never giving up. | The relentless pace of technological change makes it difficult for policy to keep up. | relentless / relentlessly / relentlessness |
| 82 | relevant | adjective | Closely connected with what is being discussed; applicable. | The passage cites only the most relevant research, omitting studies with weaker methodology. | relevant / relevance / relevantly / irrelevant |
| 83 | resilient | adjective | Able to recover quickly from difficult conditions; flexible. | Ecosystems with greater biodiversity tend to be more resilient in the face of environmental disturbance. | resilient / resilience / resiliently |
| 84 | resolute | adjective | Admirably purposeful, determined, and unwavering. | Despite strong opposition, the committee remained resolute in its commitment to the new regulations. | resolute / resolutely / resolution / resolve |
| 85 | rhetoric | noun | Persuasive language; language that is elaborate but lacks substance. | The passage contrasts the soaring rhetoric of the speech with the modest results that followed. | rhetoric / rhetorical / rhetorically / rhetorician |
| 86 | rigorous | adjective | Extremely thorough, exhaustive, or accurate; demanding. | Rigorous testing over three years preceded the drug's approval by the regulatory agency. | rigorous / rigorously / rigorousness / rigor |
| 87 | scrutiny | noun | Critical observation or examination; close and detailed inspection. | The proposed legislation faced intense public scrutiny before the vote was taken. | scrutiny / scrutinize / scrutinizing |
| 88 | skepticism | noun | A questioning attitude toward claims; doubt about the truth of something. | Healthy skepticism is a foundational virtue of the scientific method. | skepticism / skeptical / skeptic / skeptically |
| 89 | speculate | verb | To form a theory without firm evidence; to invest at risk. | The author refrains from speculating about motivations she cannot document. | speculate / speculation / speculative / speculatively |
| 90 | stagnant | adjective | Not flowing; not active or developing; motionless. | Economic growth in the region remained stagnant for nearly a decade following the financial crisis. | stagnant / stagnation / stagnate / stagnantly |
| 91 | subjective | adjective | Based on personal feelings or opinions rather than facts. | Art criticism is inherently subjective, reflecting the critic's own values and experiences. | subjective / subjectivity / subjectively / objective |
| 92 | subtle | adjective | So slight as to be difficult to detect; clever and indirect. | The author uses subtle changes in tone to signal a shift in the narrator's emotional state. | subtle / subtlety / subtly / subtleness |
| 93 | superficial | adjective | Existing only on the surface; not thorough or complete. | A superficial reading of the passage misses the irony embedded in the final paragraph. | superficial / superficially / superficiality |
| 94 | suppress | verb | To put an end to; to prevent from being expressed or known. | The editorial board was accused of suppressing research that contradicted the journal's preferred narrative. | suppress / suppression / suppressive / unsuppressed |
| 95 | sustainable | adjective | Able to be maintained at a certain level without depleting natural resources. | Sustainable agriculture requires balancing productivity with long-term soil and water health. | sustainable / sustainability / sustain / unsustainable |
| 96 | tangible | adjective | Perceptible by touch; clear and definite; real. | The program produced tangible improvements in graduation rates within three years. | tangible / tangibly / tangibility / intangible |
| 97 | tenuous | adjective | Very weak or slight; lacking a sound basis. | The connection the author draws between the two events is, at best, tenuous. | tenuous / tenuously / tenuousness |
| 98 | theoretical | adjective | Concerned with the theory of a subject rather than practical applications. | The model is theoretically sound but has not yet been tested under real-world conditions. | theoretical / theoretically / theory / theorize |
| 99 | undermine | verb | To weaken or damage gradually; to erode the foundation of. | Repeated failures to deliver on promises gradually undermine institutional credibility. | undermine / undermined / undermining |
| 100 | unprecedented | adjective | Never done or known before; without previous example. | The pandemic created an unprecedented disruption to global supply chains. | unprecedented / precedent / precedented |
| 101 | validate | verb | To demonstrate or support the truth or value of something. | Independent replication of the study validated the original team's findings. | validate / validation / validated / invalidate |
| 102 | viable | adjective | Capable of working successfully; feasible. | Solar energy has become a commercially viable alternative to fossil fuels in many markets. | viable / viability / viably / unviable |
| 103 | vivid | adjective | Producing powerful feelings or strong, clear images in the mind; intensely bright. | The author's vivid descriptions bring the historical setting to life for modern readers. | vivid / vividly / vividness |
ACT vocabulary study strategies
Focus on tone words
ACT author's purpose questions often come down to tone. Words like 'lament,' 'condemn,' 'celebrate,' and 'critique' signal the author's attitude.
Learn word families
ACT passages use varied vocabulary. If you know 'advocate,' you can handle 'advocacy,' 'advocating,' and related forms without confusion.
Practice reading broadly
ACT Reading passages draw from literary fiction, social science, humanities, and natural science. Read across all four domains to build vocabulary in each.
Context over memorization
For ACT, understanding a word's meaning in context is more useful than memorizing an isolated definition. Always read the surrounding sentences.
Apply your vocabulary on a real ACT
Take a full-length ACT practice exam to encounter these words in authentic Reading passages.
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