ir·ra·tio·nal
i-ˈra-sh(ə-)nəl 
ˌi(r)-
: not rational: such as
a(1)
: lacking usual or normal mental clarity or coherence
(2)
: not endowed with reason or understanding
b
: not governed by or according to reason
irrational fears
c
Greek and Latin prosody
(1)
of a syllable
: having a quantity other than that required by the meter
(2)
of a foot
: containing such a syllable
d(1)
: being an irrational number
an irrational root of an equation
(2)
: having a numerical value that is an irrational number
a length that is irrational
1
: an irrational being
Synonyms
Examples of irrational in a Sentence
Adjective
He became irrational as the fever got worse.
She had an irrational fear of cats.
Recent Examples on the Web
Tor Constantino, Mba, Forbes, 20 Nov. 2024
Comments Horror thrives in abstract spaces — the unknown, the unreal, the inexplicable, the irrational.
—Declan Gallagher and Chris Bellamy, EW.com, 31 Oct. 2024
Condé Nast, The New Yorker, 17 July 2023
But riveted mankind is hopelessly addicted to the irrational, with reliably disastrous results, planetwide.
—Alison Fishburn, Longreads, 17 Sep. 2022
See all Example Sentences for irrational 
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Adjective
The skill of setting boundaries is necessary for individuals to protect themselves, insulate against irrational guilt while prioritizing their well-being.
—Tor Constantino, Mba, Forbes, 20 Nov. 2024
Comments Horror thrives in abstract spaces — the unknown, the unreal, the inexplicable, the irrational.
—Declan Gallagher and Chris Bellamy, EW.com, 31 Oct. 2024
Noun
The book comprises portraits of healers, including W. H. R. Rivers, who treated soldiers who suffered from shell shock during the First World War, and Paul Robeson, who found solace in intuition and in the irrational.
—Condé Nast, The New Yorker, 17 July 2023
But riveted mankind is hopelessly addicted to the irrational, with reliably disastrous results, planetwide.
—Alison Fishburn, Longreads, 17 Sep. 2022
See all Example Sentences for irrational
Dictionary Entries Near irrational
Cite this Entry
“Irrational.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/irrational. Accessed 29 Nov. 2024.
Copy CitationMedical Definition
irrational
adjective
ir·ra·tio·nal
(ˈ)ir-ˈ(r)ash-nəl, -ən-ᵊl
: not rational: as
a
: lacking usual or normal mental clarity or coherence
was irrational for several days after the accident
b
: not governed by or according to reason
irrational fears
Legal Definition
irrational
adjective
ir·ra·tio·nal
ir-ˈra-shə-nəl
: not rational: as
a
: not governed by reason, mental clarity, or understanding
b
: not governed by a fair consideration of facts or evidence
irrationally
adverb
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