U`ro*pyg"i*al (?), a. [See Uropygium.] Anat.
Of or pertaining to the uropygium, or prominence at the base of the tail feathers, in birds.
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.
© Webster 1913.