reason
Cross references: 1. cause 2. think 1. rea.son \'re-z-*n\ n [ME resoun, fr. OF raison, fr. L ration-, ratio reason,] computation; akin to Goth garathjan to count, L reri to calculate, think, Gk arariskein to fit - more at ARM 1a: a statement offered in explanation or justification 1b: a rational ground or motive 1c: a sufficient ground of explanation or of logical defense 1d: the thing that makes some fact intelligible : CAUSE 2a1: the power of comprehending, inferring, or thinking esp. in orderly rat ional ways : INTELLIGENCE 2a2: proper exercise of the mind 2a3: SANITY 2b: the sum of the intellectual powers archaic 3a: treatment that affords satisfaction 3b: a formal accounting : JUSTIFIABLY, RIGHTLY - in reason 2. reason \'re-z-nin, -*n-in\ \-n*r, -*n-*r\ vb or rea.son.ing 1: to use the faculty of reason : THINK obs 2a: to take part in conversation, discussion, or argument 2b: to talk with another so as to influence his actions or opinions archaic 1: to justify or support with reasons 2: to persuade or influence by use of reason 3: to discover, formulate, or conclude by use of reason - rea.son.er n
Webster's English Dictionary