1743, from Modern Latin adiposus "fatty," from Latin adipem (nominative adeps, genitive adipis) "soft fat of animals, fat, lard," from Greek aleipha "unguent, fat," related to lipos "grease, fat" (see leave, v.). Change of -l- to -d- "prob. due to Umbrian influence" [Klein]. But it could as well be a native Italic formation from the same roots, *ad-leip-a "sticking onto."