word-forming element meaning "before," from Old French pre- and Medieval Latin pre-, both from Latin prae (adverb and preposition) "before in time or place," from PIE *peri- (source also of Oscan prai, Umbrian pre, Sanskrit pare "thereupon," Greek parai "at," Gaulish are- "at, before," Lithuanian prie "at," Old Church Slavonic pri "at," Gothic faura, Old English fore "before"), extended form of root *per- (1) "forward," hence "beyond, in front of, before."
The Latin word was active in forming verbs. Also see prae-. Sometimes in Middle English muddled with words in pro- or per-.
late 14c., disposicioun, "ordering, management, a setting in order, arrangement," also "tendency of mind, aptitude, inclination," from Old French disposicion (12c.) "arrangement, order; mood, state of mind" and directly from Latin dispositionem (nominative dispositio) "arrangement, management," noun of action from past-participle stem of disponere "to put in order, arrange" (see dispose).
Meaning "frame of mind, attitude, inclination; temperament, natural tendency or constitution of the mind" (late 14c.) are from astrological use of the word for "position of a planet as a determining influence" (late 14c.). Related: Dispositional.
"incline beforehand, put into a certain frame of mind, render susceptible either mentally or physically," 1640s, perhaps a back-formation from predisposition or else from or based on French predisposer (15c.). Related: Predisposed; predisposing.