# Definition of irrational in English:

## irrational

Pronunciation: /ɪˈraʃ(ə)n(ə)l/

1Not logical or reasonable: irrational feelings of hostility
More example sentences
• Power sets the guidelines by which we measure what is reasonable and what is irrational.
• The more irrational and illogical someone becomes, the more logical and incisive I become.
• By absurd, I do not mean silly, but absurd as is in the illogical or irrational.
Synonyms
unreasonable, illogical, groundless, baseless, unfounded, unjustifiable, unsound;
absurd, ridiculous, ludicrous, silly, foolish, senseless, nonsensical, laughable, idiotic, stupid, wild;
untenable, implausible, unscientific, arbitrary
British informal barmy, daft
1.1Not endowed with the power of reason.
Example sentences
• Whenever you encounter a system that seems so irrational, you should ponder what's going on beneath the surface.
• Man is an irrational being, morals are irrational, and have no metaphysical foundation which make them "real" or worth paying any attention to.
2 Mathematics (Of a number, quantity, or expression) not expressible as a ratio of two integers, and having an infinite and non-recurring expansion when expressed as a decimal. Examples of irrational numbers are the number π and the square root of 2.
Example sentences
• What about a seed angle derived from the golden ratio, an irrational number?
• The square root of 2 is an irrational number because it can't be written as a ratio of two integers.
• How can mathematical concepts like points, infinitesimally small quantities, or irrational numbers be anything but products of our minds?

## noun

Mathematics
An irrational number or quantity; a surd.
Example sentences
• Eudoxus's definition of equal ratios corresponds exactly to the modern theory of irrationals.
• Whether such quirks in the irregularity of irrationals have any implications for number theory remains an open question for mathematicians.
• His commentary to Euclid is of interest because of its discussion of unordered irrationals.

## Derivatives

#### irrationalize

(also irrationalise) verb
Example sentences
• When one thinks of planar travel the mind can often be boggled, confused, deceived and irrationalized.
• The absence of knowledge affects human behaviour by reducing, distorting, and irrationalising the choices made by individuals.
• I have reason to believe that she is about to irrationalize thinking on every issue.

## Origin

Late Middle English: from Latin irrationalis, from in- 'not' + rationalis (see rational).

## Words that rhyme with irrational

national, passional, rational

Line breaks: ir|ration¦al

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