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What is the Meaning of “Fallacious”?

Fallacious
/fəˈleɪʃəs/
adjective C2 Tier 5 (Rare) formal academic

Based on a mistake or false reasoning; logically wrong even if it seems convincing.

Definition of Fallacious

Quick Meaning of Fallacious

Based on a mistake or false reasoning; logically wrong even if it seems convincing.

Detailed Definition of Fallacious

Based on a false or mistaken belief; logically invalid

How to Pronounce Fallacious

IPA: /fəˈleɪʃəs/
fal la cious

Stress pattern: oOo (3-syllable word).

Tip: fə-LAY-shəs. Stress second syllable (LAY). Three syllables: fal-LA-cious.

Watch out: Some learners say 'fal-AY-shus'. Correct: fə-LAY-shəs.

Full pronunciation guide for “fallacious” →

Origin and Etymology of Fallacious

From Latin 'fallaciosus' (deceptive), from 'fallacia' (deception), from 'fallere' (to deceive, fail).

How to Use Fallacious in a Sentence

Each example shows “fallacious” with a CEFR level so learners can pick examples that match their fluency.

  • “The fallacious reasoning in the advertisement appealed to emotion rather than logic.”
    C2 formal
  • “Her fallacious conclusion ignored critical evidence that contradicted her thesis.”
    C2 academic
  • “The fallacious argument mistakenly assumed all teenagers are irresponsible.”
    C2 written

Synonyms and Antonyms of Fallacious

Common Synonyms for Fallacious

Smart Synonyms for Fallacious — When to Use Each

false
Not true without reasoned basis
unsound
Not logically valid emphasized flaw
invalid
Not legally binding or just

Antonyms of Fallacious

See all synonyms for “fallacious” →

Common Collocations with Fallacious

These phrases pair with “fallacious” in everyday English:

  • fallacious reasoning
  • fallacious argument
  • fallacious logic
  • fallacious conclusion

Common Mistakes When Using Fallacious

Even fluent speakers slip up with “fallacious”. Here’s how to avoid the most common errors:

✗ Wrong: Incorrect use of fallacious.
✓ Correct: Correct use of fallacious.
Why: See usage tip for correct usage context.
✗ Wrong: Another incorrect use of fallacious.
✓ Correct: Another correct use of fallacious.
Why: See collocations for typical uses.
✗ Wrong: Third incorrect use of fallacious.
✓ Correct: Third correct use of fallacious.
Why: Review the main meaning and usage tip.

Other Forms of Fallacious

Frequently Asked Questions About Fallacious

What is the meaning of "Fallacious"?

Based on a mistake or false reasoning; logically wrong even if it seems convincing.

How do you pronounce "Fallacious"?

The IPA is /fəˈleɪʃəs/. fə-LAY-shəs. Stress second syllable (LAY). Three syllables: fal-LA-cious.

What part of speech is "Fallacious"?

"Fallacious" is an adjective at C2 level (Common European Framework).

What are synonyms for "Fallacious"?

Common synonyms include false, incorrect, unsound.

How do you use "Fallacious" in a sentence?

For example: "The fallacious reasoning in the advertisement appealed to emotion rather than logic."

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