"part of the human body where pelvis and thigh join," Old English hype "hip," from Proto-Germanic *hupiz (source also of Dutch heup, Old High German huf, German Hüfte, Swedish höft, Gothic hups "hip"), of uncertain origin. In architecture, "external angle at the junction of two sides of a roof," from late 17c. Hip-flask, one meant to fit in a hip pocket, is from 1923. Related: Hips.