'Uropygial gland' definitions:

Definition of 'uropygial gland'

(from WordNet)
noun
Oil-secreting gland situated at the base of the tail in most birds [syn: uropygial gland, preen gland]

Definition of 'Uropygial gland'

From: GCIDE
  • Uropygial \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. [1913 Webster]
  • 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. [1913 Webster]