Rock

Rock can be any of the following:

1. In geology, a rock is a substance composed of minerals and classified according to mineral composition.
2. In music, rock is a short form for the phrase "rock and roll", but also refers to a harder form of music derived from rock and roll.
3. A small offshore islet lacking or with minimal soil.
4. The Rock is slang for Alcatraz, a federal prison in San Francisco Bay, and about which an action movie was produced in 1995; see The Rock
5. Rock is a confectionery made and sold in many of the UK's seaside holiday resorts. As the character Ida says in Graham Greene's novel Brighton Rock, "It's like those sticks of rock: bite it all the way down, you'll still read Brighton."
6. Slang for a jewel, usually understood to be a diamond. As in, "Did you get a load of that rock on her finger."