D defs.my
Entry 1 sense Webster, 1913

Uropygial

· U·ro·pyg·i·al · IPA /jʊəɹə(ʊ)ˈpɪd͡ʒɪəl/
01 a. Of or pertaining to the uropygium, or prominence at the base of the tail feathers, in birds.
  1. 1.
    Of or pertaining to the uropygium, or prominence at the base of the tail feathers, in birds.(Anat.)
Phrases & compounds
Uropygial gland — a peculiar sebaceous gland at the base of the tail feathers in most birds. It secretes an oily fluid which is spread over the feathers by preening.