- signal (n.)
- late 14c., from Old French signal, from Medieval Latin signale "a signal," from Late Latin signalis (adj.) "used as a signal, pertaining to a sign," from Latin signum "signal, sign" (see sign (n.)).
- signal (v.)
- 1805, from signal (n.). Related: Signaled; signaling. Earlier verb was signalize (1650s).
- signal (adj.)
- "remarkable, striking, notable" 1641, from French signalé, past participle of signaler "to distinguish" (see signal (n.)).