irrational
irrational (ir*rash"un*al) , adjective
[Latin irrationalis: compare French irrationnel. See In- not, and Rational.]
1.
Not rational; void of reason or understanding; as, brutes are irrational animals.
2.
Not according to reason; having no rational basis; clearly contrary to reason; easily disproved by reasoning; absurd; -- of assertions and beliefs.
foolish; unreasonable.
It seemed utterly irrational any longer to maintain it.
3.
(Mathematics) Not capable of being exactly expressed by an integral number, nor by a ratio of integral numbers; surd; -- said especially of roots. See Surd.