extrapolate

IPA/ɪkˈstræpəleɪt/
KK[ɛkstrˈæpəlˌet]IPA/ɪkˈstræpəleɪt/

extrapolate — verb

  • extrapolatepresent simple I / you / we / they
  • extrapolateshe / she / it
  • extrapolatedpast simple
  • extrapolating-ing form

1. to form a judgment about something unknown by using facts or patterns you alread

1.verbtransitive / intransitiveB2
Definition

to form a judgment about something unknown by using facts or patterns you already have, often to predict what may come next or how a situation will develop.

Example

Dr. Amara used past infection rates to extrapolate next month's case numbers.

extrapolate + direct object (predicted number)

Elena's test results were used to extrapolate how the medicine might affect older adults.

passive: [data] + were used to extrapolate + how-clause

Common collocations
  • extrapolate from data
  • extrapolate trends
  • extrapolate results
  • extrapolate findings
  • broadly extrapolate
  • extrapolate backwards / forwards
  • extrapolate a pattern
Synonyms
  • infer

    broader — to reach a conclusion from evidence; 'infer' can be about any kind of reasoning, while 'extrapolate' always projects beyond the known data

  • project

    closer in meaning, but 'project' often suggests a formal calculation or forecast, while 'extrapolate' can be a mental estimate

  • forecast

    more specific to weather, economic, or business predictions; 'extrapolate' is the method, 'forecast' the result

  • deduce

    more logical / certain — you deduce what follows necessarily; you extrapolate what might probably happen

Grammar Patterns

extrapolate + from + [data/information/pattern]

extrapolate + that-clause

extrapolate + direct object

extrapolate from + noun + that-clause (mixed)

Usage Note

Common in academic, scientific, and business contexts. The object is usually a future outcome, estimate, or trend. Frequently used with 'from' to name the source of information. The intransitive pattern ('we can only extrapolate from what we know') is also natural in formal speech.

Common Mistakes

I extrapolated that she was feeling sad.
I inferred that she was feeling sad.
'extrapolate' is about projecting from data, not reading emotions from behaviour.
The scientist extrapolated the result without any basis.
The scientist extrapolated the result from the existing data.
always state what the projection is based on; avoid leaving the source unclear.

Word family

Synonym discussion

Sense: verb/1

While infer, project, forecast, deduce, and predict all involve reasoning about something that is not directly known, extrapolate specifically means using known data points to estimate values or outcomes beyond that range. Infer is broader — you can infer someone's mood from their tone, but you would not extrapolate a mood. Project and forecast are more formal and usually involve calculations, whereas extrapolate can be a mental estimate without formulas. Deduce implies a logical necessity (2 + 2 = 4), while extrapolate holds less certainty — it is a reasonable guess. Predict is a general term for saying what will happen; extrapolate is one method of making a prediction. For example: 'From three months of sales data, the team extrapolated that annual revenue would reach $2 million.' Here, project would sound slightly more formal but equally natural, while predict would be too general to show the data-driven method.

infer ↗project ↗forecast ↗deduce ↗predict ↗

Common collocations

Nouns

Adverbs

Phrases

  • based on
  • on the basis of
  • from what we know

Prepositions

Etymology

LatinEnglish

Extrapolate is a blend created in the 1800s from the Latin prefix 'extra-' meaning 'outside' or 'beyond' and a shortened form of 'interpolate' (to insert between known points). Mathematicians first used it to describe estimating values outside a known data range, and the word later spread to general use for any reasoned guess beyond the facts at hand.