English Reference
noun · verb

conjecture

n. · v.
US /kənˈdʒɛkʃɝ/ UK /kəndʒˈɛktʃɐ/ con·jec·ture UK spelling conjectured, conjectures

  1. 01 C1 Advanced Formal

    n.an opinion or idea you form without having all the facts.

    n.a conclusion or proposition based on incomplete evidence; a supposition that lacks definitive proof.

    Simple

    The news report was based on conjecture rather than hard evidence.

    In context

    The historian admitted that his theory about the king's disappearance was mere conjecture, as no contemporary documents survived the fire.

    Usage

    Often used as an uncountable noun when referring to the act of guessing.

    guesssuppositionspeculation
  2. 02 C1 Advanced Technical Math

    n.a mathematical statement that appears to be true but has not been proven by logic yet.

    n.a mathematical proposition which has been conjectured to be true, but for which no proof has yet been found.

    Simple

    The mathematician spent years trying to prove the famous conjecture.

    In context

    Goldbach's conjecture remains one of the oldest and best-known unsolved problems in number theory and all of mathematics.

    Usage

    In this domain, it is a countable noun referring to a specific named problem.

  3. 03 C1 Advanced Formal

    v.to form an opinion or reach a conclusion using only a little information.

    v.to infer from inconclusive evidence; to propose a hypothesis without formal verification.

    Simple

    Scientists conjecture that there may be water deep under the planet's surface.

    In context

    Archaeologists conjecture that the site served as a ceremonial center, though the lack of artifacts makes a definitive conclusion impossible.

    Usage

    Can be used transitively with a 'that' clause or as an intransitive verb.

    speculatesurmisehypothesize

His killing, which remained unsolved for decades, gave rise to fervent conspiracy theories and conjecture.

The Guardian· 15 Aug 2026

Because not one of Custer’s men lived to tell the tale, exactly what happened next has been a matter of conjecture ever since, inspiring an almost infinite number of conflicting story lines.

Smithsonian Magazine· 24 Jun 2026

From Old French, from Latin coniectūra (“a guess”), from coniectus, perfect passive participle of cōniciō (“throw or cast together; guess”), from con- (“together”) + iaciō (“throw, hurl”); see jet. Compare adjective, eject, inject, project, reject, subject, object, trajectory, deject, abject, surjection, bijection, interject. Compare typologically Russian прики́дывать (prikídyvatʹ) (akin to кида́ть (kidátʹ)).

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Level C1 · Advanced
Frequency Frequent
Updated