Cue (noun)

1. A signal to start or continue an action.
2. A suggestion or hint to prompt an action or thought.
3. A long, narrow stick used to strike the ball in games such as pool, billiards, and snooker.
4. A line spoken by an actor to prompt the delivery of another's line in a play or movie.
5. A recognizable feature or characteristic that can be used to identify or distinguish something.

Origin:

Middle english que, from old french queue, from latin cauda ("tai.l")

Examples:

1. The drummer gave the cue for the band to start playing.
2. She gave him a cue to begin his speech.
3. He lined up his shot with the cue.
4. The stage manager gave the actors their cues for the next scene.
5. The bright red flowers were a cue that spring had arrived.