Unit of measure Meaning, Definition & Usage

(as of length, surface, volume, dry measure, liquid measure, money, weight, time, and the like), in general, a determinate quantity or magnitude of the kind designated, taken as a standard of comparison for others of the same kind, in assigning to them numerical values, as 1 foot, 1 yard, 1 mile, 1 square foot, 1 square yard, 1 cubic foot, 1 peck, 1 bushel, 1 gallon, 1 cent, 1 ounce, 1 pound, 1 hour, and the like; more specifically, the fundamental unit adopted in any system of weights, measures, or money, by which its several denominations are regulated, and which is itself defined by comparison with some known magnitude, either natural or empirical, as, in the United States, the dollar for money, the pound avoirdupois for weight, the yard for length, the gallon of 8.3389 pounds avoirdupois of water at 39.8° Fahr. (about 231 cubic inches) for liquid measure, etc.; in Great Britain, the pound sterling, the pound troy, the yard, or ¹⁄₁₀₈₇₁₉ part of the length of a second's pendulum at London, the gallon of 277.274 cubic inches, etc.; in the metric system, the meter, the liter, the gram, etc.