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irrational - 5 dictionary results

ir⋅ra⋅tion⋅al

   [i-rash-uh-nl]
–adjective
1. without the faculty of reason; deprived of reason.
2. without or deprived of normal mental clarity or sound judgment.
3. not in accordance with reason; utterly illogical: irrational arguments.
4. not endowed with the faculty of reason: irrational animals.
5. Mathematics.
a. (of a number) not capable of being expressed exactly as a ratio of two integers.
b. (of a function) not capable of being expressed exactly as a ratio of two polynomials.
6. Algebra. (of an equation) having an unknown under a radical sign or, alternately, with a fractional exponent.
7. Greek and Latin Prosody.
a. of or pertaining to a substitution in the normal metrical pattern, esp. a long syllable for a short one.
b. noting a foot or meter containing such a substitution.
–noun
8. Mathematics. irrational number.
Origin:
1425–75; late ME < L irratiōnālis. See ir- 2 , rational
Dictionary.com Unabridged (v 1.1)
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2006.
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ir·ra·tion·al     (ĭ-rāsh'ə-nəl)  Pronunciation Key 
adj.  
    1. Not endowed with reason.
    2. Affected by loss of usual or normal mental clarity; incoherent, as from shock.
    3. Marked by a lack of accord with reason or sound judgment: an irrational dislike.
    4. Being a syllable in Greek and Latin prosody whose length does not fit the metric pattern.
    5. Being a metric foot containing such a syllable.
    1. Being a syllable in Greek and Latin prosody whose length does not fit the metric pattern.
    2. Being a metric foot containing such a syllable.
  3. Mathematics Of or relating to an irrational number.

n.   Mathematics
An irrational number.

ir·ra'tion·al·ly adv., ir·ra'tion·al·ness n.
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2006 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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irrational 
c.1470, "not endowed with reason" (of beats, etc.), from L. irrationalis "without reason," from in- "not" + rationalis "reason" (see reason). Meaning "illogical, absurd" is attested from 1641.

Online Etymology Dictionary, © 2001 Douglas Harper
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irrational

adjective
1. not consistent with or using reason; "irrational fears"; "irrational animals" [ant: rational] 
2. real but not expressible as the quotient of two integers; "irrational numbers" [ant: rational] 

noun
1. a real number that cannot be expressed as a rational number [syn: irrational number] 

WordNet® 3.0, © 2006 by Princeton University.
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Irrational

Ab*surd"\, a. [L. absurdus harsh-sounding; ab + (prob) a derivative fr. a root svar to sound; not connected with surd: cf. F. absurde. See Syringe.] Contrary to reason or propriety; obviously and fiatly opposed to manifest truth; inconsistent with the plain dictates of common sense; logically contradictory; nonsensical; ridiculous; as, an absurd person, an absurd opinion; an absurd dream.

This proffer is absurd and reasonless. --Shak.

'This phrase absurd to call a villain great. --Pope. --p. 9

Syn: Foolish; irrational; ridiculous; preposterous; inconsistent; incongruous.

Usage: Absurd, Irrational, Foolish, Preposterous. Of these terms, irrational is the weakest, denoting that which is plainly inconsistent with the dictates of sound reason; as, an irrational course of life. Foolish rises higher, and implies either a perversion of that faculty, or an absolute weakness or fatuity of mind; as, foolish enterprises. Absurd rises still higher, denoting that which is plainly opposed to received notions of propriety and truth; as, an absurd man, project, opinion, story, argument, etc. Preposterous rises still higher, and supposes an absolute inversion in the order of things; or, in plain terms, a "putting of the cart before the horse;" as, a preposterous suggestion, preposterous conduct, a preposterous regulation or law.

Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.
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