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.

Quantum mania has become a staple of the tech sector, dismissed by some as irrational exuberance.

From Barron's • May 6, 2026

John says at first the changes were attributed to the menopause, but in March 2023 he noticed his wife had become more irrational and did not react as expected when she had a car crash.

From BBC • May 6, 2026

We’re clinging to that belief but will concede that it may be irrational.

From Slate • May 2, 2026

“In view of the current robust demand for AI cloud services, we are not concerned that Tencent’s deeper involvement in the AI cloud market would lead to irrational competition.”

From The Wall Street Journal • Mar. 23, 2026

Zero would clash with this doctrine, and unlike the irrational, zero could be ignored.

From "Zero: The Biography of a Dangerous Idea" by Charles Seife

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