engraving or carving in low relief on a stone (as in a brooch or ring)
"The antique brooch features a tiny cameo of Aphrodite carved from shell, catching the light whenever she moves."
A piece of jewelry, etc., carved in relief.
"The antique brooch featured a tiny cameo depicting a classical scene in white shell against dark glass."
To appear in a cameo role.
"The famous actor made a brief but memorable cameo at the end of the movie."