late 14c., preposicioun, in grammar, "indeclinable part of speech regularly placed before and governing a noun in an oblique case and showing its relation to a verb, adjective, or other noun," from Latin praepositionem (nominative praepositio) "a putting before, a prefixing," noun of action from past-participle stem of praeponere "put before," from prae "before" (see pre-) + ponere "put, set, place" (past participle positus; see position (n.)). In grammatical use, a loan-translation of Greek prothesis, literally "a setting before." Old English used foresetnys as a loan-translation of Latin praepositio.
Old English profost, "local governor, representative of a king in a country or district," reinforced by Old French cognate provost, both from Late Latin propositus, from Latin propositus/praepositus "a chief, prefect" (source of Old Provençal probost, Old High German probost, German Propst), literally "placed before, in charge of," past participle of praeponere "put before" (see preposition).
Provost marshal, "military officer who acts as head of police in a district, town, camp, etc., to preserve order and punish offenses against military discipline," is attested from 1510s.
Latin adverb and preposition of separation in space, meaning "down from, off, away from," and figuratively "concerning, by reason of, according to;" from PIE demonstrative stem *de- (see to). Also a French preposition in phrases or proper names, from the Latin word.
word-forming element common in words of French and Latin origin, meaning primarily "through," thus also "throughout; thoroughly; entirely, utterly," from Latin preposition per (see per (prep.)).