noun 1. a unit or standard of measurement: weights and measures. 2. a system of measurement: liquid measure. 3. an instrument, as a graduated rod or a container of standard capacity, for measuring. 4. the extent, dimensions, quantity, etc., of something, ascertained especially by comparison with a standard: to take the measure of a thing. 5. the act or process of ascertaining the extent, dimensions, or quantity of something; measurement.