Longman Dictionary of Contemporary English - pearl

~ n 1 »JEWEL« 2 a) a small round hard white object with a silvery shine, that is formed inside the shell of an oyster, and is very valuable as a jewel  (a string of pearls | a pearl necklace) b) an artificial copy of this jewel 3 »LIQUID« literary a small round drop of some liquid  (Pearls of dew sparkled on the grass.) 4 »HARD SUBSTANCE« a hard shiny, variously coloured substance formed inside some shellfish, which is used for decorating objects; mother­of­pearl  (a knife with a pearl handle) 5 »EXCELLENT THING/PERSON« C usually singular someone or something that is especially good or valuable  (a pearl among women | a pearl beyond price)  (Good health is a pearl beyond price.) 6 cast pearls before swine to give something valuable to someone who does not understand its value 7 pearls of wisdom an expression meaning wise remarks, often used jokingly to mean slightly stupid remarks  (Have you any more pearls of wisdom you'd like to share with us?)