Meanings
comparative more irrational · superlative most irrational
- Not rational; unfounded, nonsensical or wrong-headed.
an irrational decision
1 more example
July 18, 2012, Scott Tobias, AV Club The Dark Knight Riseshttps://web.archive.org/web/20130918201706/http://www.avclub.com/articles/the-dark-knight-rises-review-batman,82624/ Where the Joker preys on our fears of random, irrational acts of terror, Bane has an all-consuming, dictatorial agenda that’s more stable and permanent, a New World Order that’s been planned out with the precision of a military coup.
- not comparablearithmeticOf a real number, that cannot be written as the ratio of two integers.
The number π is irrational.
Antonyms: rational
plural irrationals
- mathematicsA real number that can not be expressed as the quotient of two integers, an irrational number.
The square root of 2, which was the first irrational to be discovered, was known to the early Pythagoreans, and ingenious methods of approximating to its value were discovered.
1946, Bertrand Russell, History of Western Philosophy, I.24
Synonyms & antonyms
adjectiveOf a real number, that cannot be written as the ratio of two integers.
More synonyms by meaning
adjectivenot consistent with or using reason
adjectivereal but not expressible as the quotient of two integers
nouna real number that cannot be expressed as a rational number
Synonym sets from Open English WordNet, CC BY 4.0.
Origin
- Latinirratiōnālis
- Englishirrational
From Latin irratiōnālis, from ir- + ratiōnālis.
More words from Latin
Full word history & related roots →Translations
Ancient Greek ἄλογος, ἄρρητος
- ἄλογος (álogos)unfounded or nonsensical
- ἄρρητος (árrhētos)mathematics: of a number
Bulgarian неразумен, безразсъден
- неразумен (nerazumen)unfounded or nonsensical
- безразсъден (bezrazsăden)unfounded or nonsensical
- ирационален (iracionalen)mathematics: of a number
- ирационално число (iracionalno čislo)irrational number
Catalan bèstia, irracional
- bèstiaunfounded or nonsensical
- irracionalunfounded or nonsensical
- irracionalmathematics: of a number
Chinese Mandarin 不合理, 無理數 /无理数
- 不合理 (bùhélǐ)unfounded or nonsensical
- 無理數 /无理数 (wúlǐshù)mathematics: of a number
Czech iracionální
- iracionálnímathematics: of a number
Danish irrationel, irrational
- irrationelunfounded or nonsensical
- irrationalmathematics: of a number
Dutch irrationeel, irrationele
- irrationeelunfounded or nonsensical
- irrationeleunfounded or nonsensical
- onzinnigunfounded or nonsensical
- onzinnigeunfounded or nonsensical
- onredelijkunfounded or nonsensical
- onredelijkeunfounded or nonsensical
- irrationaalmathematics: of a number
- irrationalemathematics: of a number
Esperanto malracia, neracionala
- malraciaunfounded or nonsensical
- neracionalamathematics: of a number
Finnish epälooginen, irrationaalinen
- epälooginenunfounded or nonsensical
- irrationaalinenunfounded or nonsensical
- irrationaalinenmathematics: of a number
French irrationnel, irrationnel
- irrationnelunfounded or nonsensical
- irrationnelmathematics: of a number
German irrational, irrationell
- irrationalunfounded or nonsensical
- irrationellunfounded or nonsensical
- unvernünftigunfounded or nonsensical
- irrationalmathematics: of a number
Greek άρρητος
- άρρητος (árritos)mathematics: of a number
Hindi अपरिमेय
- अपरिमेय (aprimey)mathematics: of a number
Hungarian észszerűtlen, irracionális
- észszerűtlenunfounded or nonsensical
- irracionálisunfounded or nonsensical
- irracionálismathematics: of a number
Icelandic óræður, óræð tala
- óræðurmathematics: of a number
- óræð talairrational number
Irish aingiallta
- aingialltaunfounded or nonsensical
Italian irrazionale
- irrazionaleunfounded or nonsensical
Japanese 不合理な, 無理な
- 不合理な (fugōri na)unfounded or nonsensical
- 無理な (muri na)unfounded or nonsensical
- 理不尽な (rifujin na)unfounded or nonsensical
- ばかげた (bakageta)unfounded or nonsensical
- 筋違いな (sujichigai na)unfounded or nonsensical
- 無理数 (murisū)mathematics: of a number
Korean 불합리한, 무리수
- 불합리한 (bulhamnihan)unfounded or nonsensical
- 무리수 (murisu)mathematics: of a number
- 무리수 (murisu)irrational number
Māori heahea, kewha
- heaheaunfounded or nonsensical
- kewhamathematics: of a number
Norwegian Bokmål irrasjonell, irrasjonal
- irrasjonellunfounded or nonsensical
- irrasjonalmathematics: of a number
Polish nieracjonalny, irracjonalny
- nieracjonalnyunfounded or nonsensical
- irracjonalnyunfounded or nonsensical
- niewymiernymathematics: of a number
- liczba niewymiernairrational number
Portuguese irracional, irracional
- irracionalunfounded or nonsensical
- irracionalmathematics: of a number
Romanian irațional, nerațional
- iraționalunfounded or nonsensical
- neraționalunfounded or nonsensical
Russian нерациона́льный, иррациона́льный
- нерациона́льный (neracionálʹnyj)unfounded or nonsensical
- иррациона́льный (irracionálʹnyj)unfounded or nonsensical
- иррациона́льный (irracionálʹnyj)mathematics: of a number
Spanish irracional
- irracionalunfounded or nonsensical
Swedish irrationell, irrationell
- irrationellunfounded or nonsensical
- irrationellmathematics: of a number
Tagalog atbang, maatbang
- atbangunfounded or nonsensical
- maatbangunfounded or nonsensical
- ditagwayinmathematics: of a number
- bilang na ditagwayinirrational number
Vietnamese bất hợp lý, số vô tỉ
- bất hợp lýunfounded or nonsensical
- số vô tỉmathematics: of a number
Rhymes & wordplay
Rhymes with irrational
Cite this entry
irrational. (n.d.). In WatkinsX Dictionary. Retrieved November 2, 2026, from https://dictionary.watkinsx.com/word/irrational
“irrational.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/irrational. Accessed November 2, 2026.
WatkinsX Dictionary, s.v. “irrational,” accessed November 2, 2026, https://dictionary.watkinsx.com/word/irrational.
Source: irrational on Wiktionary, CC BY-SA 4.0.