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.

She did some moves that were pretty irrational, and she would have times where she would act on impulse, and it became more and more unstable and unsafe.

From Los Angeles Times • May 13, 2026

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

From MarketWatch • May 12, 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

My fear is irrational; this is just a test, it isn’t real.

From "Divergent" by Veronica Roth

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!