uropygial gland(n = noun.animal) preen gland - oil-secreting gland situated at the base of the tail in most birds;
is a kind of oil gland
is a part of bird

adrenal gland, anterior pituitary gland, apocrine gland, bartholin's gland, bulbourethral gland, central vein of suprarenal gland, cowper's gland, digestive gland, duct gland, ductless gland, eccrine gland, endocrine gland, exocrine gland, gland, gland disease, green gland, honey gland, lachrymal gland, lacrimal gland, lymph gland, male reproductive gland, mammary gland, mandibular gland, meibomian gland, nabothian gland, oil gland, parathyroid gland, parotid gland, peter's gland, pineal gland, pituitary gland, posterior pituitary gland, preen gland, prostate gland, salivary gland, sebaceous gland, sex gland, silk gland, sublingual gland, sublingual salivary gland, submandibular gland, submandibular salivary gland, submaxillary gland, submaxillary salivary gland, sudoriferous gland, suprarenal gland, sweat gland, tarsal gland, tear gland, thymus gland, thyroid gland, uropygial, vestibular gland