WordNet sense 1 (an inclined metal frame at the front of a locomotive to clear the track):

cowcatcher, fender, pilot

WordNet sense 2 ((computer science) a part of RAM used for temporary storage of data that is waiting to be sent to a device; used to compensate for differences in the rate of flow of data between components of a computer system):

buffer storage, buffer store

WordNet sense 3 (a power tool used to buff surfaces):

polisher

WordNet sense 4 (an implement consisting of soft material mounted on a block; used for polishing (as in manicuring)):

buff

WordNet sense 5 (protect from impact):

cushion, soften