is a specific kind of: system of weights, weight.

has as a part: avoirdupois unit.

is a specific kind of: bodily property.

is a broader term that covers: adiposeness, adiposity, fattiness | abdominousness, paunchiness | greasiness, oiliness, oleaginousness | corpulency, fleshiness, obesity | steatopygia.

is the opposite of: leanness, spareness, thinness.

derivation: fat, fatten, fatten out, fatten up, fill out, flesh out, plump, plump out | fat | blubbery.