irrationally

American

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

adverb

in a way that is contrary to reason or is not sensible; illogically.

In firing a highly competent CEO without cause, the Board acted unlawfully, unreasonably, and irrationally.
Stick to your simple calculation and logic, even when markets are behaving irrationally.
in a way that is driven by impulse or instinct rather than reason; without having or being able to use the faculty of reason.

When a reporter started poking around, the suspect began acting irrationally and took off like a wild animal.

Other Word Forms

nonirrationally adverb

Etymology

Origin of irrationally

First recorded in 1640–50; irrational ( def. ) + -ly ( def. )

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.

Some American stocks are being irrationally hit by fears of disruption by artificial intelligence.

From Barron's • Feb. 10, 2026

I found myself irrationally angry about the way T-Mobile convinced the Backstreet Boys to parody “I Want It That Way” with facile sloganeering.

From Slate • Feb. 8, 2026

Needham’s Berg also notes that one pocket of software that has irrationally been swept up in the selloff this week is human-resources and payroll software.

From MarketWatch • Feb. 7, 2026

I can sometimes get irrationally upset by movies with an incredible premise that is poorly executed.

From Salon • Feb. 16, 2025

Karl the Fog burned Rishi’s nose, and he felt suddenly, irrationally angry at a weather pattern.

From "When Dimple Met Rishi" by Sandhya Menon

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023