Antonym: rational. Similar words: rational, rationalize, national, aberration, educational, nationalism, international, organizational. Meaning: [ɪ'ræʃənl] 
n. a real number that cannot be expressed as a rational number. adj. 1. not consistent with or using reason 2. real but not expressible as the quotient of two integers.
n. a real number that cannot be expressed as a rational number. adj. 1. not consistent with or using reason 2. real but not expressible as the quotient of two integers. 
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1) It's totally irrational, but I'm frightened of mice.
2) The rational and the irrational complement each other. Individually, they are far less powerful.
3) She was prey to irrational fears.
4) She has an irrational dread of hospitals.
5) Integers, rational numbers,(http://sentencedict.com/irrational.html) and irrational numbers are all real.
6) After taking the drug she became completely irrational.
7) His parents were worried by his increasingly irrational behaviour.
8) His behaviour was becoming increasingly irrational.
9) She couldn't help it if she was being irrational.
10) The weight of irrational guilt pressed on her.
11) He dismissed her fears as irrational.
12) 95% of patients know their obsessions are irrational.
13) We must not pander to the irrational prejudices of a small minority.
14) Since the attack, she had fallen prey to irrational fears.
15) He's becoming increasingly irrational.
16) This, you understand, is purely sentimental and wholly irrational.
17) His behaviour can be somewhat irrational at times.
18) But Bruce's irrational behaviour spoiled it all.
19) By implication, other approaches were based on irrational behaviour.
20) Fighting hard to prevent such losses is not irrational.
21) The terrifying irrational has no place in classical mythology.
22) Vance is becoming increasingly irrational.
23) I seethed with a totally irrational rage.
24) I become now as irrational as I was then.
25) This idea has spawned irrational diets that defy science, cause much inconvenience, and may even threaten nutrition.
26) As irrational as it sounds, many companies hire new workers and then turn around and slash their payrolls.
27) To opt out at this moment would be quite irrational.
28) He had stopped taking his medication and had become violent and irrational.
29) The crude and splenetic expression and presentation of such views suggested irrational pathological prejudice rather than a coherent ideology.
30) The court may then find that, if unexplained, it is irrational.
More similar words: rational, rationalize, national, aberration, educational, nationalism, international, organizational, constitutional convention, emotional, ratification, additional, functional, gratification, traditional, conventional, traditionally, proportional, zonation, donation, instructional, institutional, constitutional, unconditionally, operation, unconstitutional, migration, probationary, reparation, separation.