SIGNAL

noun

1. A sequence of states representing an encoded message in a communication channel.
2. Any variation of a quantity or change in an entity over time that conveys information upon detection.
3. A sign made to give notice of some occurrence, command, or danger, or to indicate the start of a concerted action.

verb

1. To indicate; to convey or communicate by a signal.
2. To communicate with (a person or system) by a signal.

adjective

1. Standing above others in rank, importance, or achievement.