uropygial

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u·ro·py·gi·um

U0151900 (yo͝or′ə-pī′jē-əm, -pĭj′ē-)n. The posterior part of a bird's body, from which the tail feathers grow.
[New Latin ūropygium, from Greek ouropugion : ouro-, tail; see uro-2 + pugē, rump.]
u′ro·py′gi·al (-əl) adj.