noun

1. Obsolete any signaling apparatus
2. an apparatus or system that converts a coded message into electric impulses and sends it to a distant receiver: originally, Morse code signals were sent using a key that opened and closed the circuit to activate an electromagnetic sounder, but now teletypewriters, computers, radio and microwave signals, satellites, and lasers are used

Etymology: Fr télégraphe: see tele- & -graph: orig. used of a semaphore

transitive verb

1. to send (a message) by telegraph
2. to send a telegram to
3. Informal to signal (an intended action, decision, etc.) unintentionally to another, as by a gesture or look

intransitive verb