"that which is obtained or offered as the reward of exertion or contest; reward or symbol of victory," spelling alteration of Middle English prise (c. 1300 in this sense), from Old French pris "price, value, worth; reward" (see price (n.)). Figuratively, "anything worth striving for," from c. 1600. As an adjective, "worthy of a prize," from 1803. The spelling with -z- is from late 16c. Prize-fighter is from 1703; prize-fight (one for a prize) from 1730.
"a person worth a million dollars, pounds, francs, etc.," 1821, from French millionnaire (1762); see million. The first in America is said to have been John Jacob Astor (1763-1848).