irrational

B2 Topic:Describing Qualities

US /ɪˈɹæʃ.(ə.)nəl/ See IPA manual

Freq #11587

Meanings

1

adj
Not based on clear thinking or good reasons

He has an irrational fear of spiders.
2

adj
In maths, describing a number that cannot be written as a simple fraction

The number pi is irrational.
3

noun
In maths, a number that cannot be written as a fraction of two whole numbers

The square root of two was the first irrational the Greeks discovered.

Thesaurus

Synonyms

3 noun · in maths, a number that... irrational number

Word family

Derived forms irrationalismirrationalistirrationalisticirrationalityirrationalizationirrationalizeirrationallyirrationalnessnonirrational

Appears in

Phrases (1)

See all

irrational number
a real number that cannot be expressed as one integer divided by another

Adjective + noun

Etymology

From Latin irratiōnālis, from ir- + ratiōnālis.

irratiōnālis Latin

View etymology graph ->

Topics

Describing Qualities

External links

# irrational

**Type:** Word
**Level:** B2
**Part of speech:** adj, noun
**IPA (US):** /ɪˈɹæʃ.(ə.)nəl/
**Frequency rank:** 11587

## Meanings
1. Not based on clear thinking or good reasons
2. In maths, describing a number that cannot be written as a simple fraction
3. In maths, a number that cannot be written as a fraction of two whole numbers

## Examples
- He has an irrational fear of spiders.
- The number pi is irrational.
- The square root of two was the first irrational the Greeks discovered.

## Derived Forms
- irrationalism
- irrationalist
- irrationalistic
- irrationality
- irrationalization
- irrationalize
- irrationally
- irrationalness
- nonirrational

## Roots and Affixes
- Root: irratiōnālis
- Affix: ir- - not

## Etymology
From Latin irratiōnālis, from ir- + ratiōnālis.

## AI Etymology
Irrational comes from Latin irratiōnālis, from ir- + ratiōnālis. The analysis is mainly morphological: the modern adjectival form is built from the named base and affix.

## Topics
- Describing Qualities

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