Webster's Revised Unabridged Dictionary · 1913

Uropygial

Uropygial , adjective

[See Uropygium.]

(Anatomy) Of or pertaining to the uropygium, or prominence at the base of the tail feathers, in birds.
Collocations (1)
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.