PrepScholar's Top 150 ACT Vocabulary Words

Reading & Writing Definition

adhere

verb

stick completely to a surface or substance* [or] believe in and

follow the practices of

aloof

adjective

not friendly or forthcoming; cool and distant

ambiguous

adjective

open to more than one interpretation; having a double meaning

analyze

verb

examine in detail, typically for purposes of explanation and

interpretation (analysis, analytical)

anecdote

noun

a short and amusing or interesting story about a real incident or

person

antagonize

verb

cause someone to become hostile

anticipate

verb

regard as probable; expect or predict

apprehensive

adjective

anxious or fearful that something bad will happen

arcane

adjective

mysterious or secret

assert

verb

state a fact or belief confidently and forcefully

assess

verb

evaluate or estimate the nature, ability, or quality of

attribute

verb

regard something as being caused by someone or something

bear

verb

endure an ordeal or difficulty

befall

verb

(of something bad) happen to someone

burgeon

verb

begin to grow or increase rapidly; flourish

coherent

adjective

logical and consistent

compassion

noun

concern for the sufferings or misfortunes of others

compensate (for)

verb

make up for something unwelcome or unpleasant by exerting an

opposite force or effect

complement

noun

a thing that completes or brings to perfection a larger whole

compose verb

1. write or create* 2. constitute, make up (composition, composed

of)

condescending

adjective

having or showing a feeling of superiority

consecutive

adjective

following continuously; in unbroken or logical sequence

contour

noun

an outline, especially one representing or bounding the shape or

form of something

contract

verb

decrease in size, number, or range

contradict

verb

be in conflict with

correlate verb

have a mutual relationship or connection (corollary, correlated)

corollary

noun

a direct or natural consequence or result

critical

adjective

1. expressing adverse or disapproving comments or judgments 2.

expressing or involving an analysis of the merits and faults of a

work of literature, music, or art* 3. involving the objective analysis

and evaluation of an issue in order to form a judgment* 4. (of a

situation or problem) having the potential to become disastrous; at

a point of crisis

cumbersome

adjective

1. large or heavy and therefore difficult to carry or use 2. slow or

complicated and therefore inefficient*

deficit

noun

the amount by which something is too small

demean

verb

cause a severe loss in the dignity of and respect for someone or

something

depict

verb

show or represent

determine verb

1. cause (something) to occur in a particular way; be the decisive

factor in 2. ascertain or establish exactly, typically as a result of

research or calculation*

PrepScholar's Top 150 ACT Vocabulary Words

devoid

adjective

entirely lacking or free from

differentiate

verb

1. recognize or ascertain what makes (someone or something)

different* 2. (differentiate between) identify differences between

(two or more things or people) 3. make (someone or something)

appear different or distinct 4. make or become different in the

process of growth or development

diffuse

adjective

spread out over a large area; not concentrated

digress

verb

leave the main subject temporarily in speech or writing

diminish

verb

make or become less

discrepancy

noun

a lack of compatibility or similarity between two or more facts

(dis)inclined

adjective

willing or positive about an action, belief, or attitude (disinclined:

unwilling or negative about something)

dismay

verb

consternation and distress, typically that caused by something

unexpected

disposition

noun

1. a person's inherent qualities of mind and character* 2. an

inclination or tendency

dynamic

adjective

characterized by constant change, activity, or progress

eclipse

noun

a loss of significance, power, or prominence in relation to another

person or thing

emerge

verb

become apparent, important, or prominent

eminent

adjective

famous and respected within a particular sphere or profession

engage verb

1. occupy, attract, or involve (someone's interest or attention) 2.

(engage someone in) cause someone to become involved in (a

conversation or discussion) 3. (engage in) participate or become

involved in*

engross

verb

absorb all the attention or interest of

ethereal

adjective

extremely delicate and light in a way that seems too perfect for this

world

evolve verb

develop gradually, especially from a simple to a more complex form

exploit

verb

1. make full use of and derive benefit from* 2. use a situation or

person in an unfair or selfish way

facilitate

verb

make an action or process easy or easier

feign

verb

pretend to be affected by a feeling, state, or injury

fleeting

adjective

lasting for a very short time

glaring

adjective

extremely obvious or conspicuous

hardship

noun

severe suffering or deprivation

hurtle

verb

move or cause to move at a great speed, typically in an

uncontrolled manner

immerse

verb

involve oneself deeply in a particular activity or interest* [or] dip or

submerge in a liquid

imminent

adjective

about to happen

(im)mobile

adjective

able to move or be moved freely or easily (immobile: not able to be

moved)

impervious

adjective

unable to be affected by

incendiary

adjective

1. tending to stir up conflict* 2. designed to cause fires

incompetent

adjective

not having or showing the necessary skills to do something

successfully

(in)conceivable

adjective

capable of being imagined or grasped mentally (inconceivable: not

capable of being imagined)

(in)dissoluble

adjective

able to be dissolved, loosened, or disconnected (indissoluble: solid,

not able to be broken apart)

inevitable

adjective

certain to happen; unavoidable

PrepScholar's Top 150 ACT Vocabulary Words

infer verb

deduce or conclude (information) from evidence and reasoning

rather than from clear statements (inference)

integrate

verb

combine one thing with another so that they become a whole

intuition

noun

the ability to understand something immediately, a 'gut feeling'

justify

verb

1. show or prove to be right or reasonable* 2. be a good reason for

lack

verb

be without or deficient in

latent

adjective

existing but not yet developed or obvious; hidden; concealed

lethargic

adjective

sluggish and apathetic

mere

adjective

used to emphasize how small or insignificant someone or

something is

minute

adjective

extremely small (pronouned MY-noot)

mishap

noun

an unlucky accident

nostalgia

noun

a sentimental longing or affection for the past

notion

noun

a conception of or belief about something

obsolete

adjective

no longer produced or used; out of date

obstruct

verb

to be or get in the way of; prevent; hinder

omit verb

leave out or exclude (someone or something), either intentionally or

forgetfully

orient

verb

align or position something relative to a known point or landmark

paradox

noun

an idea that, despite sound (or apparently sound) reasoning from

acceptable premises, leads to a conclusion that seems senseless,

logically unacceptable, or self-contradictory

pensive

adjective

engaged in, involving, or reflecting deep or serious thought

peril

noun

serious and immediate danger

perpetual

adjective

occurring repeatedly; so frequent as to seem endless and

uninterrupted

ponder

verb

think about something carefully

potent

adjective

having great power, influence, or effect

precede verb

1. come before (something) in time 2. come before in order or

position* (preceding)

predate

verb

exist or occur at a date earlier than something

principle

noun

a fundamental truth or proposition that serves as the foundation for

a system of belief or behavior

proficient

adjective

competent or skilled in doing or using something

profound

adjective

1. very great or intense* 2. having or showing great knowledge or

insight

pungent

adjective

having an intensely strong taste or smell

redundant adjective

not or no longer needed or useful

reflect verb

1. (of a surface or body) throw back (heat, light, or sound) without

absorbing it 2. (of a mirror or shiny surface) show an image of 3.

embody or represent (something) in a faithful or appropriate way

4. (reflect well/badly on) bring about a good or bad impression of:

the incident reflects badly on the operating practices of the airlines.

5. (reflect on/upon) think deeply or carefully about*

relevant adjective

closely connected or appropriate to the matter at hand (antonym:

irrelevant)

resent

verb

feel bitterness or slight anger at a circumstance, action, or person

revive

verb

1. to regain life, consciousness, or strength 2. restore interest in or

the popularity of*

PrepScholar's Top 150 ACT Vocabulary Words

rudimentary

adjective

1. involving or limited to basic principles 2. of or relating to an

immature, undeveloped, or basic form*

sensory

adjective

of or relating to sensation or the physical senses; transmitted or

perceived by the senses

skeptical

adjective

not easily convinced; having doubts or reservations

solemn

adjective

formal and dignified; serious

static

adjective

lacking in movement, action, or change

superlative

adjective

of the highest quality or degree

sustainable

adjective

1. able to be maintained at a certain rate or level 2. conserving an

ecological balance by avoiding depletion of natural resources*

trait

noun

a distinguishing quality or characteristic

trivial

adjective

of little value or importance

(un)realized

adjective

give actual or physical form to (unrealized: not given form to, such

as 'unrealized plans' to have a picnic on a rainy day)

void

noun

a completely empty space

wholly

adverb

entirely; fully

A blue background indicates a high-frequency word.

An asterisk (*) indicates the definition of the word that is more/most

likely to appear on the ACT.

Science

Definition

abundant

adjective existing or available in large quantities; plentiful

altitude

noun the height of an object or point in relation to sea level or ground level

attribute

noun a quality or feature regarded as a characteristic or inherent part of

someone or something

characteristic

adjective

typical of a particular person, place, or thing

combustion

noun

the process of burning something

conduct(ivity)

verb

transmit a form of energy such as heat or electricity (conductivity:

the effectiveness of a material at conducting energy)

correspond

verb

have a close similarity; match or agree almost exactly

decelerate

verb

reduce the speed of; lose velocity; move more slowly

deposition

noun

the process of some substance being naturally deposited

somewhere

distinguish

verb

recognize or treat (someone or something) as different

efficient

adjective

being effective without wasting time or effort or expense; able to

accomplish a purpose; functioning effectively

emit

verb

give off, send forth, or discharge; as of light, heat, or radiation,

vapor, etc.

erode

verb

remove soil or rock; become ground down or deteriorate

evolution

noun

a process in which something passes by degrees to a different

stage (especially a more advanced or mature stage)

exert

verb

put to use; make a great effort at a mental or physical task

exhibit

verb

show an attribute, property, knowledge, or skill; to show, make

visible or apparent

fuse

verb

mix together different elements; join

gauge

verb

measure precisely and against a standard; determine the capacity,

volume, or contents of by measurement and calculation

generalize

verb

draw from specific cases for more general cases

PrepScholar's Top 150 ACT Vocabulary Words

given

adjective

specified or stated: Students' understanding of any given topic.

hypothesis

noun

a tentative theory about the natural world; a concept that is not yet

verified but that if true would explain certain facts or phenomena

incremental

adjective

increasing gradually by regular degrees or additions

intact

adjective

undamaged in any way; whole

interval

noun

the distance between things; a definite length of time marked off by

two instants

larvae

noun

the active immature form of an insect, especially one that differs

greatly from the adult and forms the stage between egg and pupa,

e.g., a caterpillar or grub.

latter

noun

the second of two or the second mentioned of two

mass

noun

the quantity of matter that something contains

maturation

noun

coming to full development; becoming mature

onset

noun

the beginning or early stages

precipitation

noun

the falling to earth of any form of water (rain or snow or hail or sleet

or mist)

prolong

verb

lengthen or extend in duration or space

directly

proportional

adjective

a relationship between two connected amounts, factors or

quantities in which an increase in one causes an increase in the

other;

inversely

proportional

adjective

a relationship between two connected amounts, factors or

quantities in which an increase in one causes a decrease in the

other

residual

adjective

relating to or indicating a remainder; something left after other parts

have been taken away

solution

noun

a homogeneous mixture of two or more substances; frequently (but

not necessarily) a liquid solution

substrate

noun

any substance or layer lying underneath another; a surface on

which an organism grows or is attached; the substance that is

acted upon by an enzyme or ferment

trial

noun

a specific experiment or set of experiments within a larger context

uniform

adjective

evenly spaced; always the same; showing a single form or

character in all occurrences

variable

noun

in an experiment: an element, feature, or factor that is changed

within the experiment to determine its effects