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.

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

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

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

From MarketWatch • May 12, 2026

I didn’t want to admit that I was being held hostage by my irrational mother.

From "The Red Umbrella" by Christina Gonzalez

Vocabulary lists containing irrational

Pi Day Vocabulary

Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!

The Number System

Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!

Divergent

Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!