n. 1 See sign, 1, above. 2 incitement, stimulus, spur, impetus, goad, prick The waving of the flag will be the signal to advance
adj. 3 remarkable, conspicuous, striking, extraordinary, unusual, unique, singular, special, noteworthy, notable, exceptional, significant, important, outstanding, momentous, consequential, weighty The British forces won a signal victory at Khartoum that day Winning the competition is a signal accomplishment.
v. 4 motion, indicate, gesture, gesticulate, communicate, announce, notify; whistle, wink, blink, nod, beckon, wave, sign When your turn comes, a clerk will signal you to approach the counter Peter raised his hand as a request to leave the room and the teacher signalled his assent.