n. An instrument for determining the specific gravities of bodies, whether liquid or solid. See hydrometer.n. An instrument for measuring the force of gravity against some elastic force. There have been many attempts to construct such instruments, but none has been successful.n. Specifically, a copper vessel of one cubic foot capacity, with a heavy plate-glass cover, used in determining the density of large-grained gunpowder inclusive of the vacant spaces between its grains. See gravimetric density of gunpowder, under density.