Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “irrational”

irrational

adjective     /ɪˈræʃənəl/
Irrational feelings and actions are based on your emotions and not on good reasons: irrational behaviour an irrational fear of flyingOf unsound mindStupid and silly
irrationality     /ɪˌræʃənˈæləti/ noun [U] irrationally adverb
(Definition of irrational adjective from the Cambridge Learner's Dictionary © Cambridge University Press)

Browse related topics

You are looking at an entry to do with Of unsound mind, but you might be interested in these topics from the Psychology, psychiatry, & psychoanalysis topic area:

Definitions of “irrational” in other dictionaries

Word of the Day

beneficiary

a person or group who receives money, advantages, etc. as a result of something else

Word of the Day

Blog

Read our blog about how the English language behaves.

Learn More

New Words

Find words and meanings that have just started to be used in English, and let us know what you think of them.

Learn More