From Longman Dictionary of Contemporary Englishlocketlock‧et /ˈlɒkɪt $ ˈlɑː-/ noun [countable] DCJa piece of jewellery that you wear around your neck on a chain, with a small metal case in which you can put a picture, a piece of hair etc
Examples from the Corpus
locket• Then it relaxed, opened, releasing a treasure it had been holding: a chain a locket, a gold locket.• And inside, in the tiny, circular locket, was the picture of a woman.• A gold locket in which two small photographs lay face to face.• The sentimental value of her lockets, chains, rings, heirlooms was not appreciated by the insurance company.• No, not every item; he kept on his locket.• Retrieving the locket, Adam sees that it contains one lock of blonde hair and another of black.• Monks tied the locket to a heavy weight and dropped it into the water.Origin locket (1300-1400) Old French locquet, from Middle Dutch loke “latch” 