means The joint where the thigh bone meets the pelvis, and the rounded part of the body on either side just below the waist.

from From Old English 'hype,' a word with deep Germanic roots — a cousin of Dutch 'heup' and German 'Hüfte.' The body-part sense is the original one; the unrelated slang 'hip' meaning fashionable or aware came much later and from murkier sources, so they only look like the same word by accident.