cutaneous appendage feather BTO:0000447 One of the epidermal growths that form the distinctive outer covering, or plumage, on birds. Feathers are formed in tiny follicles in the epidermis, or outer skin layer, that produce keratin proteins. Wikipedia:Feather GAID:1214 MESH:D005241 MAT:0000156 EFO:0000955 SCTID:410027006