The Collaborative International Dictionary
Volumenometer
Volumenometer \Vol`u*me*nom"e*ter\, n. [L. volumen volume + -meter.] (Physics) An instrument for measuring the volume of a body, especially a solid, by means of the difference in tension caused by its presence and absence in a confined portion of air.
Wiktionary
volumenometer
n. An instrument which measure the volume (3-dimensional space) of something which can't be immersed in liquid.