Definitions
1.nounA sequence of states representing an encoded message in a communication channel.
2.nounAny variation of a quantity or change in an entity over time that conveys information upon detection.
3.nounA sign made to give notice of some occurrence, command, or danger, or to indicate the start of a concerted action.
4.nounAn on-off light, semaphore, or other device used to give an indication to another person.
5.noun(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."
6.nounAn action, change or process done to convey information and thus reduce uncertainty.
7.nounA token; an indication; a foreshadowing; a sign.
8.nounUseful information, as opposed to noise.
9.nounA simple interprocess communication used to notify a process or thread of an occurrence.
10.nounA signalling interaction between cells
11.verbTo indicate; to convey or communicate by a signal.
12.verbTo communicate with (a person or system) by a signal."Seeing the flames, he ran to the control room and signalled headquarters."