signal

n

1. sign, marker, guidepost, milepost, milestone, landmark, seamark; beacon, light, flag, warning light, caution light, flare, rocket; monitor, pilot, gauge, meter, instrument; alert, warning, siren, whistle, alarm, Archaic. alarum, horn, toot, tocsin, bell; cry, call, yell, scream.

2. gesture, gesticulation, Sl. high sign; cue, tip, Sl. tip-off. See sign(def. 3).

3. password, watchword, countersign, grip; convention, Cards. play.

4. impetus, stimulus, fillip, spur, goad, prick; incentive, motive, reason, cause.

5. token, symbol; indication, mark. See sign(def. 1).

adj

6. indicative, marking; directional, signaling, semaphoric, semaphorical; pilot, guiding, lead; warning, caution, admonitory, Biol. sematic.

7. significant, historic, landmark, important, meaningful, momentous, weighty, big, consequential; outstanding, extraordinary, extraordinaire, glorious, grand, fantastic, fabulous, splendid, Inf. super, Sl. bang-up; unparalleled, nonpareil, unequaled, unprecedented; striking, impressive, breathtaking, brilliant; unbelievable, amazing, astonishing, Inf. unreal; notable, noteworthy, remarkable, unforgettable; exceptional, special, unusual, uncommon, unfamiliar, out of the ordinary, unheard of; rare, unique, singular, one of a kind. See also significant(def. 1).

v

8. gesture, gesticulate, Inf. fugle. See sign(def. 11).

9. communicate, express, speak, transmit, send, convey; semaphore, flag, Naut. wigwag; give away, tip [s.o.] off, Inf. telegraph, Inf. broadcast.

10. alert, warn, alarm, sound an alarm or siren or whistle, honk one's horn, ring a bell, scream or yell or cry out at; flash a light, light a flare, put on one's flashers, send up a rocket, shine a beacon. See also sign(def. 10).