English Reference
noun

conspiracy

n.
US /kənˈspɪɹəsi/ UK /kənspˈɪɹəsi/ con·spir·a·cy UK spelling conspiracies, conspiracy's

  1. 01 B2 Upper Intermediate Law

    a secret plan made by a group of people to do something illegal or harmful.

    a secret agreement between two or more persons to perform an unlawful or harmful act; often used in legal contexts to describe the agreement itself as a crime.

    Simple

    The police uncovered a conspiracy to steal millions of dollars from the national bank.

    In context

    The defendants were charged with criminal conspiracy after investigators found encrypted messages detailing their plan to sabotage the competitor's infrastructure.

    Usage

    Often used with the preposition 'to' followed by an infinitive verb, or 'against' followed by a person or entity.

  2. 02 B2 Upper Intermediate Informal

    a belief that a secret, powerful group is responsible for an event.

    a hypothesis or belief alleging that a secret group is responsible for a specific event or situation; frequently used as a shorthand for 'conspiracy theory'.

    Simple

    He spent all night reading a conspiracy about how the moon landing was fake.

    In context

    The rise of social media has accelerated the spread of various conspiracies regarding global health initiatives and government surveillance.

    Teacher's tip

    While technically 'conspiracy' refers to the act, in modern informal English it is very common to use it to mean the 'theory' itself.

  3. 03 C2 Proficiency TechnicalAcademic Linguistics

    when different rules in a language lead to the same result.

    a situation in which different phonological or grammatical rules within a language produce similar or related phonetic outcomes.

    Simple

    The professor explained how a conspiracy of sound changes led to the loss of the final vowel.

    In context

    In generative phonology, a conspiracy occurs when several distinct rules appear to be motivated by a single surface-level constraint.

    Usage

    Used almost exclusively in academic papers or advanced linguistics lectures.

  4. 04 C2 Proficiency Literary

    the special name for a group of ravens or lemurs.

    a collective noun used specifically for a group of ravens or, less commonly, lemurs.

    Simple

    A conspiracy of ravens gathered in the old oak tree as the sun set.

    In context

    The poet used the term 'a conspiracy of lemurs' to evoke a sense of mystery and secret communication among the forest creatures.

    Teacher's tip

    This is a 'term of venery' and is very rare in everyday speech; it is mostly found in trivia or poetic writing.

Usage conspiracy theories

It also fueled conspiracy theories from people who argued the article was being attacked “because if there was a cure for Covid then they couldn’t sell their vaccines”, he said.

The Guardian· 19 Aug 2026

Because let’s face it, that is exactly what the most paranoid of fans will have expected somebody at the heart of a massive conspiracy to say.

The Guardian· 20 Aug 2026

From Middle English conspiracie, from Anglo-Norman conspiracie, from Latin cōnspīrātiō, from conspire + -acy.

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

This entry
Origin Latin cōnspīrātiō
Level B2 · Upper Intermediate
Frequency Common
Updated