"reward," prise (c.1300 in this sense), from Old French pris "price, value, worth; reward" (see price (n.)). As an adjective, "worthy of a prize," from 1803. The spelling with -z- is from late 16c. Prize-fighter is from 1703; prize-fight from 1730 (prize-fighter from 1785).
"something taken by force," mid-13c., prise "a taking, holding," from Old French prise "a taking, seizing, holding," noun use of fem. past participle of prendre "to take, seize," from Latin prendere, contraction of prehendere "lay hold of, grasp, seize, catch" (see prehensile). Especially of ships captured at sea (1510s). The spelling with -z- is from late 16c.
"to estimate," 1580s, alteration of Middle English prisen "to prize, value" (late 14c.), from stem of Old French preisier "to praise" (see praise (v.)). Related: Prized; prizing.