Roman candle, aid to navigation, alarm, amber light, balefire, beacon, beacon fire, bell, bell buoy, blinker, blue peter, buoy, caution light, danger sign, early symptom, falling barometer, flare, fog bell, fog signal, fog whistle, foghorn, gathering clouds, glance, go light, gong buoy, green light, heliograph, high sign, international alphabet flag, international numeral pennant, kick, leer, marker beacon, nod, nudge, omen, parachute flare, pilot flag, poke, police whistle, precursor, preliminary sign, premonitory sign, premonitory symptom, prodroma, prodrome, quarantine flag, radio beacon, red light, rocket, sailing aid, semaphore, semaphore flag, semaphore telegraph, sign, signal, signal beacon, signal bell, signal fire, signal flag, signal gong, signal gun, signal lamp, signal light, signal mast, signal post, signal rocket, signal shot, signal siren, signal tower, skull and crossbones, spar buoy, stop light, storm petrel, stormy petrel, symptom, the nod, the wink, thundercloud, thunderhead, touch, traffic light, traffic signal, warning sign, warning signal, watch fire, white flag, wigwag, wigwag flag, wink, yellow flag, yellow jack
warning, early warning, caution, caveat, notice, premonition, premonishment, prediction, contraindication, lesson, dehortation, admonition, monition, alarm, handwriting on the wall, mene mene tekel upharsin, red flag
, yellow flag, fog-signal, foghorn, siren, monitor, warning voice, Cassandra, signs of the times, Mother Cary's chickens, stormy petrel, bird of ill omen, gathering clouds, clouds in the horizon, death watch, watchtower, beacon, signal post, lighthouse, sentinel, sentry, watch, watchman, watch and ward, watchdog, bandog, housedog, patrol, patrolman, vedette, picket, bivouac, scout, spy, spial, undercover agent, mole, plainclothesman, advanced guard, rear guard, lookout, cautiousness, monitor, guard camera, radar, AWACS, spy satellite, spy-in-the- sky, U2 plane, spy plane, warning, premonitory, monitory, cautionary, admonitory, admonitive, sematic, warned, forewarned, on one's guard, in terrorem, Int, beware!, ware!, take care!, look out!, fore (golf), mind what you are about!, take care what you are about!, mind!, ne reveillez pas le chat qui dort, don't wake a sleeping cat, foenum habet in cornu, caveat actor, le silence du people est la legon des rois, verbum sat sapienti, a word to the wise is sufficient, un averti en vaut deux.
alarm, alarum, larum, alarm bell, tocsin, alerts, beat of drum, sound of trumpet, note of alarm, hue and cry, fire cross, signal of distress, blue lights, war-cry, war- whoop, warning, fogsignal, foghorn, yellow flag, danger signal, red light, red flag
, fire bell, police whistle, false alarm, cry of wolf, bug-bear, bugaboo, alarming, Int, sauve qui peut!, every man for himself!, qui vive?.