Mother-Of-Pearl
/ˌmʌðər əv ˈpɜːrl/noun
The iridescent inner layer of some shells, also called nacre.
Did you know?The English phrase is a calque of French *mère de perle* or *mèreperle*, reflecting the old idea that this shining layer was the “mother” of pearls, because pearls can form inside shells lined with nacre.
Etymological Timeline
Old French
OF
mere de perle
“literally “mother of pearl,” a poetic name for the pearly inner shell layer”
Middle English
EN
mothir of perle
“an iridescent shell lining used for ornament”
16th Century
EN
mother of pearl
“the shiny nacreous material from shells”
Modern English
EN
mother-of-pearl
“the iridescent inner layer of certain mollusk shells”