solidity

Etymology

solid + -ity, from Middle French solidité, from Latin soliditās.

noun

1. The state or quality of being solid.
   If colours, sounds, tastes, and smells be merely perceptions, nothing we can conceive is possest of a real, continu'd, and independent existence; not even motion, extension and solidity, which are the primary qualities chiefly insisted on. 1739, David Hume, “Book 1, part 4, section 4”, in Treatise of Human Nature
2. Moral firmness; validity; truth; certainty.
3. (geometry) The solid contents of a body; volume; amount of enclosed space.