Irrational
Irrational adjective - Not using or following good reasoning.
Mental and irrational are semantically related. In some cases you can use "Mental" instead an adjective "Irrational".
Nearby Words: irrationality, irrationally
Mental
Mental adjective - Having or showing a very abnormal or sick state of mind.
Usage example: humane treatment of mental patients
Irrational and mental are semantically related. Sometimes you can use "Irrational" instead an adjective "Mental".
Mutual synonyms
Related pairs
Both words in one sentence
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The increasingly irrational log entries of amateur sailor Donald Crowhurst, whose mental state gradually deteriorated to the point of suicide during a solo round the world sailing race.
Source: Apocalyptic Log -
The Computer Is Your Friend.Paranoia takes many forms: A mental condition characterized by extreme and irrational suspicion.
Source: Tabletop Game / Paranoia - Having a mental or neurological condition does not, by itself, make someone insane, irrational, intellectually deficient, prone to violence, or in any way not a capable, reasonable adult.
Source: Disabled Means Helpless
Cite this Source
Mental and Irrational. (2016). Retrieved 2026, August 13, from https://thesaurus.plus/related/irrational/mental
Irrational & Mental. N.p., 2016. Web. 13 Aug. 2026. <https://thesaurus.plus/related/irrational/mental>.
Mental or Irrational. 2016. Accessed August 13, 2026. https://thesaurus.plus/related/irrational/mental.
Google Ngram Viewer shows how "irrational" and "mental" have occurred on timeline