All 4 Uses

irrational
in
The Shining
(Auto-generated)

Jack (little Jacky now he was little Jacky now dozing and mumbling on a cobwebby camp chair while the furnace roared into hollow life behind him) knew exactly how many blows it had been because each soft whump against his mother's body had been engraved on his memory like the irrational swipe of a chisel on stone.†
Chpt 4

irrational = unreasonable
Jack had always felt it was not just the sudden and irrational beating his father had administered at the dinner table but the fact that, in the hospital, their mother had corroborated their father's story while holding the hand of the parish priest.†
Chpt 4
He had collapsed in his flapping and untucked hospital whites, dead possibly even before he hit the industrial black-and-red hospital tiles, and three days later the man who had dominated Jacky's life, the irrational white ghost-god, was under ground.†
Chpt 4
He glanced at the shelves again in wild, irrational hope but the shelves were just as empty as before.†
Chpt 4 *

Definitions:

(1) (irrational)
not reasonable
(2) (meaning too rare to warrant focus)
More rarely, irrational numbers in mathematics are numbers that cannot be expressed as a fraction consisting of only an integer in the numerator and denominator. For example, pi is an irrational number while 1/3 is rational.