Piezometer \Pi`e*zom"e*ter\, n. [Gr. ? to press + -meter: cf. F. pi['e]zom[`e]tre.] 1. (Physics) An instrument for measuring the compressibility of liquids. [1913 Webster] 2. (Physics) A gauge connected with a water main to show the pressure at that point. [1913 Webster] Piffero