mother-of-pearl

Short definition from Wiktionary

Noun

1. 1
   The hard pearly inner layer of certain mollusk shells; nacre.
2. 2
   A butterfly of the genus Salamis.
3. 3
   Alternative form of mother-of-pearl.

Adjective

1. 1
   Made from or looking like mother-of-pearl; iridescent or pearly.