gravimeter gra vuh mee ter n a measuring instrument for determining the specific gravity of a liquid or solid n a measuring instrument for measuring variations in the gravitational field of the earth Usage(s) He has put together 15 crack geologic field parties, ten gravimeter and 15 seismographic crews, 36 wildcat rigs. All of the experiments were finally set up, but it was learned later that a key instrumentthe surface gravimeterhad jammed. Synonym(s) hydrometer gravity meter