# fallacious

/fəˈɫeɪʃəs/ (US) · /fælˈeɪʃəs/ (UK) · CEFR C1 · Adjective

Source: https://englishreference.com/word/fallacious
Updated: 2026-10-16

## Definition

based on wrong thinking or false reasons, so it looks true but is not. You use it for arguments or ideas that sound right but have a hidden mistake.

For teachers: containing a logical error or based on unsound reasoning, so that the conclusion does not follow. Often describes arguments, claims, or beliefs that appear valid but are misleading.

## Examples

- That is a fallacious argument with no real proof.
- The lawyer showed the jury why the fallacious claim about the contract could not be trusted.
- The editorial exposed the fallacious assumption that rising house prices alone prove a healthy economy, ignoring wage stagnation and debt.

## Synonyms

flawed, invalid, unsound

## Antonyms

valid, sound

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