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irrational - 7 dictionary results

ir⋅ra⋅tion⋅al

  [i-rash-uh-nl]
Use irrational in a Sentence
–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

Related forms:
ir⋅ra⋅tion⋅al⋅ly, adverb
ir⋅ra⋅tion⋅al⋅ness, noun

Synonyms:
3. unreasonable, ridiculous; insensate.
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
Cite This Source Link To irrational
ir·ra·tion·al   (ĭ-rāsh'ə-nəl)   
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 © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Irrational

Ir*ra"tion*al\, a. [L. irrationalis: cf. F. irrationnel. See In- not, and Rational.]

1. Not rational; void of reason or understanding; as, brutes are irrational animals.

2. Not according to reason; absurd; foolish.

It seemed utterly irrational any longer to maintain it. --I. Taylor.

3. (Math.) Not capable of being exactly expressed by an integral number, or by a vulgar fraction; surd; -- said especially of roots. See Surd.

Syn: Absurd; foolish; preposterous; unreasonable; senseless. See Absurd.
Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.
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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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Main Entry: ir·ra·tio·nal
Pronunciation: ir-'ra-sh&-n&l
Function: adjective
: not rational: as a : not governed by reason, mental clarity, or understanding b : not governed by a fair consideration of facts or evidence; broadly : ARBITRARY irrational decision to deny the permit> —ir·ra·tio·nal·i·ty /ir-"ra-sh&-'na-l&-tE/ noun —ir·ra·tio·nal·ly adverb
Merriam-Webster's Dictionary of Law, © 1996 Merriam-Webster, Inc.
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Main Entry: ir·ra·tio·nal
Pronunciation: (')ir-'(r)ash-n&l, -&n-&l
Function: adjective
: not rational: as a : lacking usual or normal mental clarity or coherence irrational for several days after the accident> b : not governed by or according to reason<irrational fears> —ir·ra·tio·nal·i·ty /(")ir-"(r)ash-&-'nal-&t-E/ noun plural -ties
—ir·ra·tio·nal·ly /(')ir-'(r)ash-n&-lE, -&n-&l-E/ adverb
Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.
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irrational ir·ra·tion·al (ĭ-rāsh'ə-nəl)
adj.
Not rational; marked by a lack of accord with reason or sound judgment.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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