hip (n.1)
"part of the body where pelvis and thigh join," Old English hype "hip," from Proto-Germanic *hupiz (cognates: Dutch heup, German Hüfte, Gothic hups "hip"), from PIE *qeub- "to bend." Hip of a roof is from late 17c.
hip (n.2)
"seed pod" (especially of wild rose), Old English heope, hiope "seed vessel of the wild rose," from Proto-Germanic *hiup- (cognates: dialectal Norwegian hjupa, Old Saxon hiopo, Dutch joop, Old High German hiafo, dialectal German Hiefe, Old English hiopa "briar, bramble").
hip (adj.)
"informed," 1904, apparently originally in black slang, probably a variant of hep (1), with which it is identical in sense, though it is recorded four years earlier.
hip (interj.)
exclamation used to introduce a united cheer (compare hip-hip-hurrah), 1827, earlier hep; compare German hepp, to animals a cry to attack game, to mobs a cry to attack Jews (see hep (2)); perhaps a natural sound (such as Latin eho, heus).