TOEFL Vocabulary List: Academic Words for the iBT

accentuate verbC1

To make a feature more noticeable or prominent.

The second chart accentuates the widening gap between urban and rural incomes.

allude verbC1

To refer to something indirectly or in passing.

The preface alludes to a methodological dispute that is never fully addressed.

attest verbC1

To provide clear evidence or proof of something.

The sheer volume of citations attests to the paper's influence in the field.

authenticate verbC1

To prove or confirm that something is genuine.

Experts used X-rays to authenticate the painting as an early Rembrandt.

culminate verbC1

To reach a final or climactic point after a period of development.

The research programme culminated in a framework now used across the sector.

necessitate verbC1

To make something necessary as a result or consequence.

The unexpected results necessitated a revision of the original methodology.

nullify verbC1

To make something of no value or effect.

Confounding variables threatened to nullify any apparent link between diet and attainment.

overestimate verbC1

To judge something to be larger, better or more important than it really is.

The professor believes the reading overestimates how many jobs the factory would create.

posit verbC2

To put forward an idea or premise as a basis for argument or discussion.

The paper posits a causal link between urbanisation and declining fertility.

accretion nounC2

The gradual growth of a body through the accumulation of additional material.

The planets are thought to have formed by the accretion of dust and rock around the young Sun.

ambivalence nounC1

The state of having mixed or contradictory feelings about something or someone.

Her ambivalence about the move showed in the way she kept unpacking and repacking the same box.

carrion nounC2

The decaying flesh of dead animals.

Vultures feed almost exclusively on carrion, helping to limit the spread of disease.

chlorophyll nounC1

The green pigment in plants that absorbs light energy for photosynthesis.

In autumn, the leaves stop producing chlorophyll, revealing the yellow and orange pigments beneath.

corollary nounC1

A proposition that follows naturally from one already proved or accepted.

Greater freedom carries as its corollary a greater weight of responsibility.

detritus nounC2

Dead organic material, such as fallen leaves and animal remains, that is gradually broken down.

Earthworms feed on the detritus that accumulates on the forest floor.

domestication nounC1

The process of taming wild animals or cultivating wild plants for human use over many generations.

The domestication of wheat in the Fertile Crescent transformed human settlement patterns.

eccentricity nounC2

The degree to which an orbit deviates from a perfect circle.

Changes in the eccentricity of Earth's orbit occur over cycles of about 100,000 years.

ethnography nounC2

The detailed descriptive study of a particular culture, usually based on long-term fieldwork.

Her ethnography of a fishing village in Norway became a model for later fieldworkers.

feudalism nounC2

A medieval social system in which peasants worked land for lords in exchange for protection.

The Black Death weakened feudalism because labour shortages let peasants demand higher wages.

fissure nounC1

A long, narrow crack in rock or in the ground.

Lava poured out of a fissure several kilometres long.

floodplain nounC1

An area of low-lying ground beside a river that is subject to flooding.

Planners were criticised for approving new homes on the floodplain.

foreshadowing nounC1

A literary technique in which hints are given about events that will happen later in the story.

The storm in the opening chapter is a clear piece of foreshadowing.

germination nounC2

The process by which a seed begins to sprout and grow into a new plant.

Some pine seeds require the heat of a forest fire before germination can occur.

homeostasis nounC2

The tendency of an organism to maintain stable internal conditions despite external change.

Sweating is one of the mechanisms the body uses to maintain homeostasis on hot days.

invertebrate nounC1

An animal that has no backbone, such as an insect, worm or jellyfish.

Invertebrates make up more than ninety per cent of all known animal species.

lichen nounC2

A slow-growing organism formed by a fungus and an alga living together, often found on rocks and bark.

Lichens are often the first organisms to colonise bare rock after a glacier retreats.

monolith nounC1

A single large block of stone shaped into or erected as a monument.

The monolith at the centre of the site weighs roughly twenty tonnes.

naturalism nounC1

A style that depicts subjects as accurately and realistically as possible.

The naturalism of these portraits, down to the wrinkles and warts, was entirely new.

permafrost nounC1

Ground that remains permanently frozen beneath the surface, typically in polar regions.

Thawing permafrost is releasing methane that had been locked away for millennia.

radiocarbon nounC2

A radioactive form of carbon whose rate of decay is measured to estimate the age of organic material.

Radiocarbon analysis of the charcoal placed the settlement at around 4000 BCE.

sarcophagus nounC2

A stone coffin, typically decorated with carvings or inscriptions.

The carvings on the sarcophagus depict scenes from the dead man's military career.

stratification nounC2

The arrangement of a society into hierarchical layers based on wealth, status, or power.

The study traced how school selection reinforced social stratification across generations.

subduction nounC2

The process by which one tectonic plate is forced beneath another and sinks into the mantle.

The professor explained that subduction along the Pacific margin accounts for the region's deep ocean trenches.

cyclical adjectiveC1

Occurring in repeated cycles over time.

Tourism here is cyclical, booming every summer and collapsing each winter.

homologous adjectiveC2

Describing body parts in different species that share an origin from a common ancestor.

A bat's wing and a human arm are homologous structures, despite their very different functions.

igneous adjectiveC2

Describing rock formed when molten material cools and solidifies.

Granite is an igneous rock that cooled slowly deep beneath the surface.

neoclassical adjectiveC1

Relating to an eighteenth-century revival of the styles of ancient Greece and Rome.

The neoclassical façade, with its columns and pediment, deliberately recalls a Roman temple.

omniscient adjectiveC2

Describing a narrator who knows the thoughts and feelings of all the characters.

Eliot uses an omniscient narrator who moves freely between the minds of her characters.

riparian adjectiveC2

Relating to or situated on the bank of a river or stream.

A ribbon of riparian woodland shaded the water and kept it cool for trout.

unsubstantiated adjectiveC2

Not supported or proven by evidence.

The lecturer points out that the claim about ancient trade routes remains unsubstantiated.