ilio-, ili- (Greek > Latin: [ile, ileum, or ilium [singular], ilia [plural], groin, flank, lower part of the body, gut, bowels, abdomen, loins, from Greek eileos, verbal of eilein to roil or twist up tightly; previously used interchangeably with ileum, but later used with os, bone [os ilium] to denote the bone of the soft parts], hip bone).

A combining form denoting the illium or one of the broad upper bones of the pelvis.