irrationalir‧ra‧tion‧al /ɪˈræʃənəl/ ●○○ AWL adjective 
Examples
an irrational fear of flying He’s becoming increasingly irrational.—irrationally adverb—irrationality /ɪˌræʃəˈnæləti/ noun [uncountable]
ExamplesEXAMPLES FROM OTHER DICTIONARIES
Thesaurus- His behaviour can be somewhat irrational at times.
- If Dane drinks even a couple of beers, he becomes irrational and even violent.
- Jane's irrational hopes began to rise as she listened to him.
- She struggled to overcome her irrational fear of the dark.
- Vance is becoming increasingly irrational.
- A man once famed for his intolerance, xenophobia and irrational rages has become a husk of his former self.
- Fighting hard to prevent such losses is not irrational.
- I knew I was being irrational but I began to fear the worst.
- In retrospect their structure seems irrational with no clear division between territorial and functional responsibilities.
- It was a pathetic gesture on my part, an irrational breach of the wall.
- This never worked, but I did it every time: tried to talk her out of her irrational ways.
- This, you understand, is purely sentimental and wholly irrational.
- Yet although these medical theories were wrong, they weren't altogether irrational.
Longman Language Activatornot logical► illogical
Collocations · Listen to your child's worries and fears, however illogical they may seem.· I found some of his arguments totally illogical.it is illogical to do something · It is illogical to sell stocks and shares when their value is low.· Because we do not know what death is, it is illogical to fear it.
► irrational something someone says or does that is irrational is not logical and often seems slightly crazy, especially because it is based only on emotions: · His behaviour can be somewhat irrational at times.· She struggled to overcome her irrational fear of the dark.
► not make sense/make no sense something that does not make sense , especially someone's behaviour, is very difficult to understand because there seems to be no logical reason for it: · I can't understand why she's so annoyed -- it doesn't make sense.· Increasing interest rates now would make no sense at all.it makes no sense to do something: · It makes no sense to invest more money in a project that is so obviously a failure.
► not hold water informal an explanation that does not hold water does not seem logical and can be easily criticized or proved to be incorrect: · His account of events simply doesn't hold water.
► not stand up an explanation that does not stand up does not seem logical and can be easily criticized or proved to be incorrect: · He might be able to convince his lawyer that he's telling the truth, but his story won't stand up in court.not stand up to criticism/analysis etc: · It's an interesting theory, but I don't think it will stand up to close examination.
► not add up informal if a set of facts or statements do not add up , they do not seem to be logically connected, even though it is difficult to say why: · Why had she left the note? It just didn't add up.· There were a few things in his story that didn't add up.
stupid behaviour, actions, ideas etc► stupid someone who is stupid or does stupid things does things that are not at all sensible and may have bad results: · You stupid boy! I've told you not to play with matches!· Withdraw the police from the area? I've never heard such a stupid idea!· Well, if you're stupid enough to skate on the lake, you deserve to fall in.· Don't you call me a stupid idiot!stupid to do something: · You'd have to be stupid not to take advantage of a great offer like this!do something stupid: · I was very drunk last night -- I hope I didn't do anything stupid.it is stupid (of somebody) to do something: · It was stupid of me to believe her of course, but I did.a stupid thing to say/do: · That was a stupid thing to say.· I didn't say you were stupid, I said it was a stupid thing to do.
► dumb especially American, spoken stupid: · She's always asking such dumb questions.· She told him Jeff was just a friend, and he was dumb enough to believe her.· Oh, I just did the dumbest thing back there, I forgot my briefcase.
► silly someone who is silly or who says silly things does or says things that are not sensible or serious, and that may make them feel embarrassed later: · Now don't be silly, get up off the floor.· You've made a lot of silly mistakes in this essay.· I have a question which might sound a bit silly.it is silly to do something: · I think you're silly to worry so much about your hair.it is silly of somebody: · That was silly of me -- I just locked the trunk and the keys are inside.silly little: · You're just a silly little boy.a silly thing to do/say: · I had locked myself out, which was a silly thing to do.
► daft British informal stupid in what you do or say, but often in a way that is also amusing: · Is this another of your daft ideas?· Don't be daft! Of course you're not too old to go clubbing.· Well, what's the daftest thing you've ever done at work?daft thing to do/say: · What a daft thing to say!daft as a brush (=used to say that someone is very daft): · She's as daft as a brush, honestly she is.
► foolish formal stupid and not thinking sensibly about the possible results of what you do: · Jan realised later that her behaviour had been very foolish.· I think the board of directors made a foolish choice that it will later regret.it is foolish (of somebody) to do something: · It was a warning she would have been foolish to ignore.
► ill-advised formal an action or plan that is ill-advised is stupid because it will probably cause problems in the future or be unsuccessful: · In an ill-advised effort to improve matters, they sent him to boarding school.· The bank claims that the company's losses are the result of an ill-advised decision to declare bankruptcy.
► unwise done without thinking carefully enough about the possible disadvantages that may result: · She knew the marriage was unwise, but she wanted a husband and a family.· A Defence Department spokesman described the comments as 'extraordinarily unwise'.· His appointment as chief executive proved to be a very unwise decision.· It's unwise to travel alone in certain parts of the city, so always take a cab.
► irrational irrational actions, feelings, or beliefs are not based on clear thinking or sensible reasons, so they are strange or hard to understand: · If Dane drinks even a couple of beers, he becomes irrational and even violent.· Jane's irrational hopes began to rise as she listened to him.irrational fear of/about something: · an irrational fear of flying
COLLOCATIONS FROM OTHER ENTRIES► an irrational fear
Word family (=one that is not reasonable)· He grew up with an irrational fear of insects.
COLLOCATIONS FROM THE CORPUSADVERB► as· First, deficit cultures are portrayed as irrational, as based on ignorance.· I become now as irrational as I was then.· He argued that it is too simplistic, and indeed ethnocentric, to dismiss such peoples as irrational and unscientific.· Blaming parents can be as irrational as suggesting that more family time can prevent asthma or diabetes.· Instead of rejecting religion out of hand as irrational, he enquired about it.· But, importantly, they can not be ignored nor can they be dismissed easily as irrational fabrications.· One can argue with Czerny's and Hummel's metronome markings, but on no grounds can they be dismissed as irrational.
NOUN► behaviour· Cognition is to do with the rational domain: logic, reasoning and problem solving uncomplicated by irrational behaviour.· By implication, other approaches were based on irrational behaviour.· But Bruce's irrational behaviour spoiled it all.· In the Cold War irrational behaviour like this acquired a sort of sacred aura.
► fear· She kept repeating to herself that it was an irrational fear, but logic did nothing to quell the lurking terror.· Even among those not so badly affected, ignorance about radiation produces powerful if sometimes irrational fear.· If your subject to these irrational fears, then use that fear as a trigger to change your attitude.· I have an irrational fear that Lucker will blank me.· It seems that anxious people condition most easily and it is thought that irrational fears are established in this way.· Again, careful teaching is important as well as loving discussion of these often irrational fears.
WORD FAMILYnounrationality ≠ irrationalityrationalerationalismrationalistrationalizationadjectiverational ≠ irrationalrationalistverbrationalizeadverbrationally ≠ irrationally
not based on clear thought or reason SYN unreasonable OPP rational, reasonable: an irrational fear of flying He’s becoming increasingly irrational.—irrationally adverb—irrationality /ɪˌræʃəˈnæləti/ noun [uncountable]