What does ‘rock’ mean?

( n ) A diamond or other precious stone. Whenever Arlene complains about being a kept woman, Mortimer gives her another rock and she shuts up.
( n ) Fast music, rock and roll. I don’t like jazz or rap–I’m a straight rock guy.
( v ) To be excellent, outstanding. It rocks that the library is going to be open on weekends.
( v ) To dance wildly to the rock and roll music of the 60s and 70s. Man, I really dig this music; let’s rock!