pearl [ME] Pearl is from Old French perle and may be based on Latin perna ‘leg’, extended to mean a leg-of-mutton-shaped water mussel (mentioned by Pliny). The Romans greatly prized fresh-water pearls, Britain’s reputation as a good source of pearls being one of the motives behind their invasion. Matthew 7:6 has provided a common idiomatic expression: ‘Neither cast ye your pearls before swine’. In Romance languages the usual word for pearl comes via Latin, from Greek margeron, possibly from some Eastern language. The word became marguerite in French, which was also used for a variety of daisy-like flowers, because they are pearly white. The word was adopted into English in the early 17th century. This is also the source of the name Margaret.