Irrational

/ɪˈræʃ.ən.əl/

Meaning & Definition

adjective

Not based on reason or logic; unreasonable.

His decision to quit his job without another offer was seen as irrational by his colleagues.

In mathematics, not expressible as a ratio of two integers.

The square root of 2 is an irrational number because it cannot be represented as a fraction.

From the Latin 'irrationalis', from 'in-' (not) + 'rationalis' (rational).

irrational exuberance

A term used to describe overly enthusiastic behavior in investors.

rational

Based on or in accordance with reason or logic.

reason

The power of the mind to think, understand, and form judgments logically.

logical

Of or according to the rules of logic or formal argument.

Crazy

That idea is totally irrational, it's crazy!

Out of one's mind

He must be out of his mind to think that's a good plan!