signal

An indicator, such as a gesture or colored light, that serves as a means of communication. synonym: gesture.

A message communicated by such means.

Something that incites action.

An impulse or fluctuating quantity, as of electrical voltage or light intensity, whose variations represent coded information.

A sequence of digital values whose variations represent coded information.

The sound, image, or message transmitted or received by means of telecommunications.

Notably out of the ordinary.

To make a signal to.