n any rotate | rotating cylindrical device that is part of a machine, especially one used to apply or reduce pressure
n a bread or variety of roller pigeon that rolls (i.e. tumbles or somersaults) backwards (cf. Penson roller, Birmingham roller, tumbler, tumbler pigeon, English Short Faced Tumbler, English Long Faced Tumbler)
n any of various aggressive birds, of the family Coraciidae, having bright blue wings and hooked beaks
n (context|TV|film) A roll of titles or (especially) credits played over film or video; television or film credits.