PURCHASE, in its common sense, that which is acquired by the payment of money or its equivalent. The original meaning of the word (O. Fr. pourchacier, pourchasser, etc., popular, Lat. pro-captiare) was to pursue eagerly, hence to acquire. Thus " purchase " was early used by the lawyers (e.g. Britton, in 1 292) for the acquirement of property by other means than inheritance or mere act of law, including acquirement by escheat, prescription, occupancy, alienation and forfeiture; more generally, purchase in law means acquisition of land by bargain or sale, according to the law of " vendor and purchaser " (see CONVEYANCING). A later development of meaning is found in the use of the word for a mechanical contrivance by which power can be excited or applied, a hold or fulcrum. This first appears (16th century) in the nautical use of the verb, to haul up a rope or cable by some mechanical device, the root idea being apparently to " gain " advantage over the rope bit by bit.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)