/yoor'euh pij"ee euhm/ , n. Ornith.
the projecting terminal portion of a bird's body, from which the tail feathers spring.
[ 1805-15; ouropýgion, var. (with ouro- URO- 2 ) of orropýgion, equiv. to orro-, comb. form of órros sacral bone + pyg ( é ) rump, buttocks + -ion dim. suffix ]