Pearl (noun)

1. A hard, round object that is typically white or iridescent and is formed within the shells of certain mollusks, especially oysters and mussels, and used as a gemstone.
2. A smooth, lustrous spherical object that is typically white or iridescent and is formed within the shells of certain mollusks, especially oysters and mussels.
3. A pale or milky white color that is typical of pearls.

Origin:

From the old english perle, from the latin perla, from the greek perlen "pearl".

Examples:

1. She wore a pearl necklace to the ball.
2. He gave her a pearl ring.
3. The pearls on the necklace were perfectly round.
4. The pearls had a beautiful iridescent sheen.
5. The oyster was opened to reveal a pearl inside.