Adjacent Words

Irrational definitions

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Webster's 1828 Dictionary

IRRA'TIONAL, a. [L. irrationalis; in and rationalis, from ratio.]
1. Not rational; void of reason or understanding. Brutes are irrational animals.
2. Not according to the dictates of reason; contrary to reason; absurd. To pursue a course of life which destroys happiness, is irrational.

WordNet (r) 3.0 (2005)

adj
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] n
1: a real number that cannot be expressed as a rational number [syn: irrational number, irrational]

Merriam Webster's

I. adjective Etymology: Middle English, from Latin irrationalis, from in- + rationalis rational Date: 14th century not rational: as a. (1) not endowed with reason or understanding (2) lacking usual or normal mental clarity or coherence b. not governed by or according to reason <irrational fears> c. Greek & Latin prosody (1) of a syllable having a quantity other than that required by the meter (2) of a foot containing such a syllable d. (1) being an irrational number <an irrational root of an equation> (2) having a numerical value that is an irrational number <a length that is irrational> • irrationality noun • irrationally adverb II. noun Date: 1646 1. an irrational being 2. irrational number

Oxford Reference Dictionary

adj. 1 illogical; unreasonable. 2 not endowed with reason. 3 Math. (of a root etc.) not rational; not commensurate with the natural numbers (e.g. a non-terminating decimal). Derivatives: irrationality n. irrationalize v.tr. (also -ise). irrationally adv. Etymology: L irrationalis (as IN-(1), RATIONAL)

Webster's 1913 Dictionary

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.

Collin's Cobuild Dictionary

If you describe someone's feelings and behaviour as irrational, you mean they are not based on logical reasons or clear thinking. ...an irrational fear of science. = unreasonable ? rational ADJ • irrationally My husband is irrationally jealous over my past loves. ADV: ADV with v, ADV adj, ADV with cl • irrationality ...the irrationality of his behaviour.

Soule's Dictionary of English Synonyms

a. 1. Brutish, brute, void of reason, without reason. 2. Absurd, unreasonable, preposterous, foolish, silly, unwise; injudicious, extravagant. 3. Demented, alienated (in mind), crazy, lunatic, aberrant. 4. (Math.) Surd.

Moby Thesaurus

abnormal, absonant, algorismic, algorithmic, aliquot, bereft of reason, bigoted, brainless, brainsick, cardinal, contradictory, contrary to reason, crackbrained, cracked, crazed, crazy, daft, decimal, deluded, demented, deprived of reason, deranged, differential, digital, disoriented, distraught, even, exponential, extravagant, extreme, extremist, fallacious, fanatic, faulty, figural, figurate, figurative, finite, flawed, flighty, foolish, fractional, haggard, hallucinated, headless, ignorant, ill-advised, ill-considered, ill-contrived, ill-devised, ill-gauged, ill-judged, illogical, imaginary, impair, impolitic, impossible, imprudent, inadvisable, inauthentic, inconclusive, incongruous, inconsequent, inconsequential, inconsiderate, inconsistent, indiscreet, inept, inexpedient, infinite, injudicious, inordinate, insane, insensate, integral, invalid, lackbrained, lean-minded, lean-witted, loco, logarithmic, logometric, loose, lunatic, mad, maddened, manic, mazed, mental, mentally deficient, meshuggah, mindless, misadvised, misguided, moon-struck, myopic, negative, non compos, non compos mentis, nonrational, nonscientific, not all there, not bright, not following, not right, numeral, numerary, numerative, numeric, odd, of little brain, of unsound mind, off, ordinal, overenthusiastic, overreligious, overzealous, pair, paralogical, pea-brained, perfervid, pin-brained, positive, possible, prime, psycho, queer, rabid, radical, rational, real, reasonless, reciprocal, reckless, self-annulling, self-contradictory, self-refuting, senseless, shortsighted, sick, slackminded, slackwitted, sophistic, stark-mad, stark-staring mad, strange, submultiple, surd, tetched, thoughtless, touched, transcendental, ultrazealous, unadvised, unauthentic, unbalanced, unconnected, unconsidered, undiscerning, unforeseeing, ungifted, unhinged, unintellectual, unintelligent, unphilosophical, unreasonable, unreasoning, unreflecting, unreflective, unsane, unscientific, unseeing, unsensible, unsettled, unsound, untalented, unthinking, unthoughtful, unwise, wandering, wild-eyed, wild-looking, without reason, witless, zealotic