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.

The faint, irrational worry that maybe I’m not who I thought I was.

From The Wall Street Journal • Jun. 12, 2026

Detective Peter Doomanis of the Los Angeles Police Department said in his declaration, filed with Carpenter's petition, that he believes the man has "developed a disturbing and irrational fixation on petitioner".

From BBC • Jun. 2, 2026

During periods of irrational exuberance, stock prices tend to rise more quickly than Wall Street’s earnings estimates.

From MarketWatch • May 26, 2026

Like to me, acting is an irrational act.

From Los Angeles Times • May 26, 2026

If you draw the diagonal—a line from one corner to the opposite corner—the irrational appears.

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

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