You use single to emphasize that you are referring to one thing, and no more than one thing.

You use single to indicate that you are considering something on its own and separately from other things like it.

Someone who is single is not married. You can also use single to describe someone who does not have a girlfriend or boyfriend.

A single room is a room intended for one person to stay or live in.

A single bed is wide enough for one person to sleep in.

A single ticket is a ticket for a journey from one place to another but not back again.

A single or a CD single is a CD which has a few short songs on it. You can also refer to the main song on a CD as a single .

Singles is a game of tennis or badminton in which one player plays another. The plural singles can be used to refer to one or more of these matches.

In cricket, a single is a hit from which one run is scored. In baseball, a single is a hit by which a batter reaches first base.