Indicates that the speaker does not have a spouse or romantic partner.

(rail transport) Having only a single track so that trains may only run in one direction at a time

Bad things or situations always come in groups or streaks, they never come in a single way.

(travel) A ticket entitling the holder to travel in one direction to a destination.

(singing) A person's voice when singing.

(radio) A modification of amplitude modulation that modulates the output signal on a single sideband only, as opposed to both sidebands.

(UK) A single yellow line painted at the side of a road to show that parking is permitted only at specified times.

Someone who sings opera professionally.

(music) The first single released from an album

plural of single-valued function