Douglas Harper's Etymology Dictionary
"abnormal accumulation of fat on the buttocks of certain races," 1822, Modern Latin, from steato- "fat, tallow," comb. form of Greek stear (genitive steatos) "solid fat, suet" (see stearin) + Greek pyge "rump, buttocks" + abstract noun ending -ia. Related: Steatopygous "having enormously fat buttocks" [Century Dictionary]; steatopygy.
Wiktionary
n. an excessive accumulation of fat on the buttocks
Wikipedia
Steatopygia (; from the Greek στέαρ stéar, "tallow" and πυγή pugḗ, "rump") is the state of having substantial levels of tissue on the buttocks and thighs. This build is not confined to the gluteal regions, but extends to the outside and front of the thighs, and tapers to the knee producing a curvaceous figure.
Usage examples of "steatopygia".
She was fascinated by their delicate little hands and feet, and their enlarged buttocks, a recognized anatomical peculiarity named steatopygia, which enabled them to store food like a camel stores water, against the contingencies of the wilderness.