Any nonverbal action or gesture that encodes a message:
— Signals from the boat suddenly stopped.

synonyms: sign, signaling.

Roget 550: indication; symbolism, symbolization; semiology, semiotics, semeiology^†, semeiotics^†; Zeitgeist.    [means of recognition: property] characteristic, diagnostic; lineament, feature, trait; fingerprint, voiceprint, footprint, noseprint [for animals]; cloven hoof; footfall; recognition (memory) 505.    [means of recognition: tool] diagnostic, divining rod; detector.    sign, symbol; index, indice^†, indicator; point, pointer; exponent, note, token, symptom; dollar sign, dollar mark.    type, figure, emblem, cipher, device; representation etc. 554; epigraph, motto, posy.    gesture, gesticulation; pantomime; wink, glance, leer; nod, shrug, beck; touch, nudge; dactylology^†, dactylonomy^†; freemasonry, telegraphy, chirology [Med.], byplay, dumb show; cue; hint etc. 527; clue, clew, key, scent.    signal, signal post; rocket, blue light; watch fire, watch tower; telegraph, semaphore, flagstaff; cresset^†, fiery cross; calumet; heliograph; guidon; headlight.    [sign (evidence) on physobj of contact with another physobj] mark, scratch, line, stroke, dash, score, stripe, streak, tick, dot, point, notch, nick.    print; imprint, impress, impression.    [symbols accompanying written text to signify modified interpretation] keyboard symbols, printing symbols; [Symbols for emphasis], red letter, italics, sublineation^†, underlining, bold font; jotting; note, annotation, reference; blaze, cedilla, guillemets^†, hachure [Topo.]; [Special Characters list], quotation marks, "; double quotes, " "; parentheses, "( )"; brackets, "[ ]"; braces, "{ }", curly brackets; arrows, slashes; left parenthesis, "("; right parenthesis, ")"; opening bracket, "["; closing bracket, "]"; left curly brace, "{"; right curly brace, "}"; left arrow, ""; forward slash, "/"; backward slash, "\\"; exclamation point, "!"; commercial at, "@"; pound sign, "#"; percent sign, "%"; carat, "^"; ampersand, "&"; asterisk, "*"; hyphen, "-"; dash, "-", "_"; em dash, "--"; plus sign, "+"; equals sign, "="; question mark, "?"; period, "."; semicolon, ";"; colon, ":"; comma, ","; apostrophe, "'"; single quote, "'"; tilde, "~". [For identification: general] badge, criterion; countercheck^†, countermark^†, countersign, counterfoil; duplicate, tally; label, ticket, billet, letter, counter, check, chip, chop; dib^†; totem; tessera^†, card, bill; witness, voucher; stamp; cacher [Fr.]; trade mark, Hall mark.    [For identification of people, on a document] signature, mark, autograph, autography; attestation; hand, hand writing, sign manual; cipher; seal, sigil [Lat.], signet, hand and seal [Law]; paraph^†, brand; superscription; indorsement^†, endorsement.    [For identification of people, to gain access to restricted (locations or information)] password, watchword, catchword; security card, pass, passkey; credentials etc. (evidence) 467; open sesame; timbrology^†; mot de passe [Fr.], mot du guet [Fr.]; pass-parole; shibboleth.    title, heading, docket.    address card, visiting card; carte de visite [Fr.].    insignia; banner, banneret^†, bannerol^†; bandrol^†; flag, colors, streamer, standard, eagle, labarum^†, oriflamb^†, oriflamme; figurehead; ensign; pennon, pennant, pendant; burgee^†, blue Peter, jack, ancient, gonfalon, union jack; banderole, old glory [U.S.], quarantine flag; vexillum^†; yellow-flag, yellow jack; tricolor, stars and stripes; bunting.    heraldry, crest; coat of arms, arms; armorial bearings, hatchment^†; escutcheon, scutcheon; shield, supporters; livery, uniform; cockade, epaulet, chevron; garland, love knot, favor.    [Of locality] beacon, cairn, post, staff, flagstaff, hand, pointer, vane, cock, weathercock; guidepost, handpost^†, fingerpost^†, directing post, signpost; pillars of Hercules, pharos; bale-fire, beacon-fire; l'etoile du Nord [Fr.]; landmark, seamark; lighthouse, balize^†; polestar, loadstar^†, lodestar; cynosure, guide; address, direction, name; sign, signboard.    [Of the future] warning etc. 668; omen etc. 512; prefigurement etc. 511.    [Of the past] trace, record &c., 551.    [Of danger] warning etc. 668, alarm etc. 669.    [of authority]. scepter etc. 747.    [of triumph]. trophy etc. 733.    [of quantity]. gauge etc. 466.    [Of Distance] milestone, milepost.    [Of disgrace], brand, fool's cap.    [For detection], check, telltale; test etc. (experiment) 463; mileage ticket; milliary^†.    notification etc. (information) 527; advertisement etc. (publication) 531.    word of command, call; bugle call, trumpet call; bell, alarum, cry; battle cry, rallying cry; angelus^†; reveille; sacring bell^†, sanctus bell [Lat.].    exposition etc. (explanation) 522, proof etc. (evidence) 463; pattern etc. (prototype) 22.    ... show more

Polish: sygnał

Any incitement to action.

An electric quantity (voltage or current or field strength) whose modulation represents coded information about the source from which it comes.

Dutch: signaal, sein

Communicate silently and non-verbally by signals or signs:
— The diner signaled the waiters to bring the menu.

synonyms: sign, signalise, signalize.

Dutch: seinen

Be a signal for or a symptom of:
— The economic indicators signal that the euro is undervalued.

synonyms: bespeak, betoken, indicate, point.

Dutch: aanduiden, wijzen op, duiden, wijzen
Polish: sygnał

Notably out of the ordinary.

Roget 151: happening etc. v.; going on, doing, current; in the wind, in the air, afloat; on foot, afoot, on the tapis^†; at issue, in question; incidental.    eventful, stirring, bustling, full of incident; memorable, momentous, signal.    ... show more

Roget 31: great; greater etc. 33; large, considerable, fair, above par; big, huge etc. (large in size) 192; Herculean, cyclopean; ample; abundant; etc. (enough) 639 full, intense, strong, sound, passing, heavy, plenary, deep, high; signal, at its height, in the zenith.    world-wide, widespread, far-famed, extensive; wholesale; many etc. 102.    goodly, noble, precious, mighty; sad, grave, heavy, serious; far gone, arrant, downright; utter, uttermost; crass, gross, arch, profound, intense, consummate; rank, uninitiated, red-hot, desperate; glaring, flagrant, stark staring; thorough-paced, thoroughgoing; roaring, thumping; extraordinary.   ; important etc. 642; unsurpassed etc. (supreme) 33; complete etc. 52.    august, grand, dignified, sublime, majestic etc. (repute) 873.    vast, immense, enormous, extreme; inordinate, excessive, extravagant, exorbitant, outrageous, preposterous, unconscionable, swinging, monstrous, overgrown; towering, stupendous, prodigious, astonishing, incredible; marvelous etc. 870.    unlimited etc. (infinite) 105; unapproachable, unutterable, indescribable, ineffable, unspeakable, inexpressible, beyond expression, fabulous.    undiminished, unabated, unreduced^†, unrestricted.    absolute, positive, stark, decided, unequivocal, essential, perfect, finished.    remarkable, of mark, marked, pointed, veriest; noteworthy; renowned.    ... show more

Roget 642: important; of importance etc. n.; momentous, material; to the point; not to be overlooked, not to be despised, not to be sneezed at; egregious; weighty etc. (influential) 175; of note etc. (repute) 873; notable, prominent, salient, signal; memorable, remarkable; unforgettable; worthy of remark, worthy of notice; never to be forgotten; stirring, eventful.    grave, serious, earnest, noble, grand, solemn, impressive, commanding, imposing.    urgent, pressing, critical, instant.    paramount, essential, vital, all-absorbing, radical, cardinal, chief, main, prime, primary, principal, leading, capital, foremost, overruling; of vital importance &c.. in the front rank, first-rate; superior etc. 33; considerable etc. (great) 31; marked etc. v.; rare etc. 137.    significant, telling, trenchant, emphatic, pregnant; tanti [Lat.].    ... show more