conjecture

American  

[kuhn-jek-cher] / kənˈdʒɛk tʃər /

noun

1. the formation or expression of an opinion or theory without sufficient evidence for proof.

2. an opinion or theory so formed or expressed; guess; speculation.

   Synonyms:

   hypothesis, theory, supposition, inference, surmise

3. Obsolete. the interpretation of signs or omens.

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verb (used with object)

conjectured, conjecturing

1. to conclude or suppose from grounds or evidence insufficient to ensure reliability.

   Synonyms:

   presume, suppose, surmise

verb (used without object)

conjectured, conjecturing

1. to form conjectures.

conjecture British  

/ kənˈdʒɛktʃə /

noun

1. the formation of conclusions from incomplete evidence; guess

2. the inference or conclusion so formed

3. obsolete interpretation of occult signs

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verb

1. to infer or arrive at (an opinion, conclusion, etc) from incomplete evidence

Related Words

See guess.

Other Word Forms

• conjecturable
  adjective
• conjecturably
  adverb
• conjecturer
  noun
• misconjecture
  verb
• nonconjecturable
  adjective
• nonconjecturably
  adverb
• preconjecture
  verb (used with object)
• unconjecturable
  adjective
• unconjectured
  adjective

Etymology

Origin of conjecture

First recorded in 1350–1400; (for the noun) Middle English, from Middle French, from Latin conjectūra “inference, reasoning,” from conject(us) “thrown together” (past participle of conicere, conjicere “to throw together, form a conclusion,” from con- con- + -icere, -jicere, combining form of jacere “to throw”) + -ūra -ure; (for the verb) late Middle English conjecturen, from Middle French, from Late Latin conjecturāre, derivative of the noun

Explanation

Can you guess what conjecture means? It's a word to use when you are not sure of something and have to "guess or surmise." You can see how the word conjecture means that you create a theory or opinion about something without basing it in fact because the original definition of conjecture, from Old French, is "interpretation of signs and omens." Since signs and omens are pretty subjective, it makes sense that the word would then move to its current meaning. However, even though it only seems like weather reports are conjectures, they are actually based on evidence!

Example Sentences

The study introduces what the authors call the "entropy conjecture" to highlight a key problem in many existing arguments.

From Science Daily • May 3, 2026

His daughter told CNN that her father had been suffering from medical issues, and the recent conjecture has been unsettling.

From The Wall Street Journal • Apr. 25, 2026

Critically, Cembalest’s argument in support of this conclusion doesn’t rest on theory or conjecture.

From MarketWatch • Apr. 6, 2026

His defence team countered that Duterte had murdered no one and that the prosecution's argument was based on "hearsay" and "conjecture", falling far short of the bar needed to confirm the charges against him.

From Barron's • Feb. 27, 2026

His conjecture that the orbits of the planets are circumscribed by the five platonic solids were no more supported by Tycho’s data than by Copernicus’.

From "Cosmos" by Carl Sagan

Related Words

• guesswork
• hunch
• hypothesis
• inference
• supposition