adjective

irrational

irrational, unreasonable, illogical

His fear of spiders is completely irrational.

His fear of spiders is completely irrational.

She made an irrational decision to quit her job.

She made an irrational decision to quit her job.

((sth.)) is irrational to be not based on reason His fear of spiders is completely irrational.

an irrational ((noun)) an ((adjective)) not based on reason She made an irrational decision.

Synonyms: unreasonable, illogical, absurd; Antonyms: rational, logical, reasonable

From the prefix 'ir-' (not) + 'rational' (based on reason). Literally 'not based on reason'.

Think of 'ir-' as meaning 'not'. So, 'not rational'. Imagine someone irrationally arguing with a robot.

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