cameo

1a :  a gem carved in relief (see ¹relief 6); especially :  a small piece of sculpture on a stone or shell cut in relief in one layer with another contrasting layer serving as backgroundb :  a small medallion (see medallion 2) with a profiled head in relief

2 :  a carving or sculpture made in the manner of a cameo

3 :  a usually brief literary or filmic piece that brings into delicate or sharp relief the character of a person, place, or event his cameos and short commentaries on men and manners — R. T. Dunlop

4 :  a small theatrical role usually performed by a well-known actor and often limited to a single scene A major star appears in a cameo in the movie.; broadly :  a brief appearance or role