Cameo

1. a small character part in a play or film, played by a distinguished actor or a celebrity.

   there are a number of celebrity cameos

   he played numerous cameo roles

2. a piece of jewellery, typically oval in shape, consisting of a portrait in profile carved in relief on a background of a different colour.

   a cameo brooch

late Middle English (in cameo (sense 2)): from Old French camahieu, cama(h)u ; later influenced by Italian cam(m)eo, from medieval Latin cammaeus, related to the Old French word.