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.

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

But Jacobs also said that “it is incredibly important to be disciplined on price” and that the company won’t “fall irrationally in love with any particular company.”

From Barron's • Jan. 5, 2026

Tom Cross KC, barrister for the two women, told the court that in deciding the clinic should continue to be registered, "the CQC has acted irrationally".

From BBC • Jun. 24, 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