irrationally
Americanadverb
-
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.
The most important lesson from that irrationally exuberant time is that overvaluation can lead to below-average returns for years — and even decades.
From MarketWatch • Mar. 13, 2026
Some American stocks are being irrationally hit by fears of disruption by artificial intelligence.
From Barron's • Feb. 10, 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
I can sometimes get irrationally upset by movies with an incredible premise that is poorly executed.
From Salon • Feb. 16, 2025
Doesn't she hear? as she stood before me in bewilderment, as though I were acting irrationally.
From "Invisible Man" by Ralph Ellison
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
