alarum(n = noun.communication) alarm, alert, warning signal - an automatic signal (usually a sound) warning of danger;
is a kind of sign, signal, signaling
has particulars: torpedo, air alert, burglar alarm, fire alarm, foghorn, fogsignal, horn, red flag, siren, alarm bell, tocsin

   See Alarm. [1913 Webster]
" The variant form alarum is now commonly restricted to an alarm signal or the mechanism to sound an alarm (as in an alarm clock.)" [1913 Webster]

alarum, n. archaic = ALARM.

Idiom:
alarums and excursions joc. confused noise and bustle.

N  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?.

N  indication, symbolism, symbolization, semiology, semiotics, semeiology, semeiotics, Zeitgeist, characteristic, diagnostic, lineament, feature, trait, fingerprint, voiceprint, footprint, noseprint, cloven hoof, footfall, recognition (memory), 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, epigraph, motto, posy, gesture, gesticulation, pantomime, wink, glance, leer, nod, shrug, beck, touch, nudge, dactylology, dactylonomy, freemasonry, telegraphy, chirology, byplay, dumb show, cue, hint, clue, clew, key, scent, signal, signal post, rocket, blue light, watch fire, watch tower, telegraph, semaphore, flagstaff, cresset, fiery cross, calumet, heliograph, guidon, headlight, mark, scratch, line, stroke, dash, score, stripe, streak, tick, dot, point, notch, nick, print, imprint, impress, impression, keyboard symbols, printing symbols, red letter, italics, sublineation, underlining, bold font, jotting, note, annotation, reference, blaze, cedilla, guillemets, hachure, quotation marks, ", double quotes, " ", parentheses, "( )", brackets, "", braces, "", left arrow, "<", right 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, "~", 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, trade mark, Hall mark, signature, mark, autograph, autography, attestation, hand, hand writing, sign manual, cipher, seal, sigil, signet, hand and seal, paraph, brand, superscription, indorsement, endorsement, password, watchword, catchword, security card, pass, passkey, credentials, open sesame, timbrology, mot de passe, mot du guet, pass-parole, shibboleth, title, heading, docket, address card, visiting card, carte de visite, 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, 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, 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, landmark, seamark, lighthouse, balize, polestar, loadstar, lodestar, cynosure, guide, address, direction, name, sign, signboard, warning, omen, prefigurement, trace, record, warning &c, alarm, scepter, trophy, gauge, milestone, milepost, brand, fool's cap, check, telltale, test, mileage ticket, milliary, notification, advertisement, word of command, call, bugle call, trumpet call, bell, alarum, cry, battle cry, rallying cry, angelus, reveille, sacring bell, sanctus bell, exposition &c (explanation), proof, pattern, indicating, indicative, indicatory, denotative, connotative, diacritical, representative, typical, symbolic, pantomimic, pathognomonic, symptomatic, characteristic, demonstrative, diagnostic, exponential, emblematic, armorial, individual, known by, recognizable by, indicated, pointed, marked, denotable, indelible, in token of, symbolically, in dumb show, ecce signum, ex ungue leonem, ex pede Herculem, vide ut supra, vultus ariete fortior.