signal

A sequence of states representing an encoded message in a communication channel.

Any variation of a quantity or change in an entity over time that conveys information upon detection.

A sign made to give notice of some occurrence, command, or danger, or to indicate the start of a concerted action.

An on-off light, semaphore, or other device used to give an indication to another person.

(of a radio, TV, telephone, internet, etc.) An electromagnetic action, normally a voltage that is a function of time, that conveys the information of the radio or TV program or of communication with another party.

“My mobile phone can't get a signal in the railway station.”

An action, change or process done to convey information and thus reduce uncertainty.

A token; an indication; a foreshadowing; a sign.

Useful information, as opposed to noise.

A simple interprocess communication used to notify a process or thread of an occurrence.

A signalling interaction between cells

To indicate; to convey or communicate by a signal.

To communicate with (a person or system) by a signal.

“Seeing the flames, he ran to the control room and signalled headquarters.”

Standing above others in rank, importance, or achievement.

“a signal exploit; a signal service; a signal act of benevolence”