"Volume" is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance (solid, liquid, gas, or plasma) or shape occupies or contains.
Applicable units are those of quantitykind:Volume
http://en.wikipedia.org/wiki/Volume
"Volume" is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance (solid, liquid, gas, or plasma) or shape occupies or contains.
$V = \int\int\int dxdydz$, where $x$, $y$, and $z$ are cartesian coordinates.
http://www.iso.org/iso/catalogue_detail?csnumber=43012