Origin: 1250–1300; Middle English resonable <
Middle French raisonnable <
Latin ratiōnābilis. See reason, -able Related formsrea·son·a·ble·ness, rea·son·a·bil·i·ty, noun
rea·son·a·bly, adverb
half-rea·son·a·ble, adjective
half-rea·son·a·b·ly, adverb
non·rea·son·a·bil·i·ty, noun
EXPANDnon·rea·son·a·ble, adjective
non·rea·son·a·ble·ness, noun
non·rea·son·a·b·ly, adverb
qua·si-rea·son·a·ble, adjective
qua·si-rea·son·a·b·ly, adverb
COLLAPSECan be confused: rational,
reasonable (see synonym note at
the current entry).
Synonyms 1. intelligent, judicious, wise, equitable.
Reasonable, rational refer to the faculty of reasoning.
Rational can refer to the reasoning faculty itself or to something derived from that faculty:
rational powers; a rational analysis. It can also mean sane or sensible:
She was no longer rational; a rational plan. Reasonable most often means sensible:
A reasonable supposition is one which appeals to our common sense. 2. equitable, fair, just.
See moderate.