Noticeable; distinguished from what is ordinary; eminent; remarkable; memorable; as, a signal exploit; a signal service; a signal act of benevolence.(adjective)
source: webster1913
noun (n)
any nonverbal action or gesture that encodes a message(noun.communication)
Example: He awaited the signal to start.
The victory was a signal for wild celebration.
source: wordnet30
an electric quantity (voltage or current or field strength) whose modulation represents coded information about the source from which it comes(noun.phenomenon)
source: wordnet30
A sign made for the purpose of giving notice to a person of some occurence, command, or danger; also, a sign, event, or watchword, which has been agreed upon as the occasion of concerted action.(noun)
source: webster1913
adjective satellite (s)
notably out of the ordinary(adj.all)
Example: The year saw one signal triumph for the Labour party.
source: wordnet30
verb (v)
communicate silently and non-verbally by signals or signs(verb.communication)
Example: The diner signaled the waiters to bring the menu.