Definitions

irrational

[ih-rash-uh-nl, -rash-nl] / ɪˈræʃ ə nl, -ˈræʃ nl /

ADJECTIVE

illogical, senseless

Synonyms

STRONGEST

aberrant absurd crazy foolish incoherent insane preposterous ridiculous stupid unreasonable unsound unwise wrong

STRONG

invalid loony raving silly wild

WEAK

brainless cockamamie delirious demented disconnected disjointed distraught fallacious flaky freaky injudicious kooky mad mindless nonsensical nutty off-the-wall reasonless sophistic specious unreasoning unstable unthinking wacky

Antonyms

STRONGEST

balanced logical rational realistic reasonable responsible sane sensible serious smart sound thoughtful well wise

WEAK

reflective stable

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Reading a review … it’s something rational that is describing something irrational.

From Los Angeles Times • May 26, 2026

Macgregor had never known her old friend to be irrational.

From The Wall Street Journal • May 23, 2026

“The current ‘flash-sale wars’ are typical competition under demand-side economies of scale but have escalated into irrational capital burn,” said Chen Tianhao, an associate professor at Tsinghua University.

From Barron's • May 23, 2026

A stop loss is an irrational tool deployed to prevent something even more irrational.

From MarketWatch • May 12, 2026

The terrifying irrational has no place in classical mythology.

From "Mythology: Timeless Tales of Gods and Heroes" by Edith Hamilton

Vocabulary lists containing irrational

Pi Day Vocabulary

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The Number System

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Divergent

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