Open English Wordnet
Nouns
(n)reason, ground, occasiona rational motive for a belief or action“the reason that war was declared”,
“the grounds for their declaration” (n)reasonan explanation of the cause of some phenomenon“the reason a steady state was never reached was that the back pressure built up too slowly” (n)reason, understanding, intellectthe capacity for rational thought or inference or discrimination“we are told that man is endowed with reason and capable of distinguishing good from evil” (n)rationality, reason, reasonablenessthe state of having good sense and sound judgment“his rationality may have been impaired”,
“he had to rely less on reason than on rousing their emotions” (n)cause, reason, groundsa justification for something existing or happening“he had no cause to complain”,
“they had good reason to rejoice” (n)reasona fact that logically justifies some premise or conclusion“there is reason to believe he is lying” Verbs
(v)reason, reason out, concludedecide by reasoning; draw or come to a conclusion“We reasoned that it was cheaper to rent than to buy a house” (v)reasonthink logically“The children must learn to reason”