means The amount of three-dimensional space something occupies, or by extension the loudness of a sound or the size of a quantity (as in a book's bulk or a year's trading).

from From Latin 'volumen,' meaning a roll or scroll — literally something rolled up, from 'volvere,' to roll or turn (also the root of 'revolve' and 'evolve'). Ancient books were rolls of papyrus, so a 'volume' was a single rolled-up scroll. The leap to space and bulk came later: a fat scroll took up more room, and the word drifted from 'how much is rolled here' to 'how much space this fills' — and eventually, by the same logic of fullness, to 'how much sound.'