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irrationality

American  
[ih-rash-uh-nal-i-tee] / ɪˌræʃ əˈnæl ɪ ti /

noun

plural

irrationalities
  1. the quality or condition of being irrational.

  2. an irrational, illogical, or absurd action, thought, etc.


irrationality British  
/ ɪˌræʃəˈnælɪtɪ /

noun

  1. the state or quality of being irrational

  2. irrational thought, action, or behaviour

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of irrationality

First recorded in 1560–70; irrational + -ity

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.

Bennett argued presciently that by kowtowing to radicals, “a great university was brought low by the very forces which modern universities came into being to oppose: ignorance, irrationality and intimidation.”

From The Wall Street Journal • Feb. 17, 2026

America's top banker Jamie Dimon, the chief executive of US bank JP Morgan, said he was worried, and Google boss Sundar Pichai told the BBC there was "irrationality" in the current AI boom.

From BBC • Jan. 10, 2026

But Panamanian President Jose Raul Mulino said Sunday that "there is no justification whatsoever for the barbarity committed," calling it "an unforgivable act of irrationality."

From Barron's • Dec. 28, 2025

It’s simply a matter of taking advantage of structural market irrationality.

From MarketWatch • Dec. 26, 2025

Like the proof of the irrationality of V2, like the discussion of simultaneity in special relativity, this is an argument in which the premise is challenged because the conclusion seems absurd.

From "Cosmos" by Carl Sagan