Synonyms for Alarm:

adj.

warning (adjective)
alerting, warning, threatening, advisory, cautionary.

n.

drum, scream, shout, hue and cry, fire alarm, cry, gong, buzzer, war cry, hoot, trumpet, the all clear, blast, car alarm, call to arms, squeal, alarm bell, yell, burglar alarm, tocsin. chronometer, analog, clock, big ben, cuckoo clock, clock radio, fob watch, trepidation, fob. chill, study at, notification. fearfulness, shake up, funk, cold feet, frighten/scare the wits out of someone, horror. close, attach, connect, automate, fit, disconnect, hook into, ground, fit out. alarm (noun)
appall, semaphore, beacon, call, bell, warning device, appal, alert, horrify, alarm system, consternation, whistle, foghorn, signal, siren, buoy, flare, alarum, alarm clock, horn, dismay, warning signal.
alarm clock (noun)
clock radio.
fear (noun)
apprehension, faintheartedness, agitation, dread, spinelessness, angst, anxiety, fright, intimidation, cowardice, timidity, fear, funk, terror.
feeling (noun)
consternation, dismay.
feeling of sudden fear (noun)
fright, anxiety, dismay, dread, cold feet, apprehension, terror, horror, trepidation, consternation, panic, scare.
tocsin (noun)
gong.
warning (noun)
caveat, threat, notice.
warning, signaling device (noun)
caution, clock, alert, signal, cry, warning, whistle, gong, scream, squeal, horn, tocsin, blast, call, drum, siren, trumpet, bell, shout, yell, buzzer.

v.

alarm (verb)
dismay, surprise, startle, shock.
emotion (verb)
appal, horrify, dismay, appall.
frighten (verb)
harrow, intimidate, agitate, horrify, terrify, disturb, frighten, petrify, scare, haunt, set on edge, panic, rattle, unnerve.
upset (verb)
frighten, terrify, startle, chill, unnerve, surprise.
warn (verb)
alert, warn, threaten, advise, caution.

Other synonyms:

analog, cuckoo clock, the all clear, burglar alarm, clock radio, big ben, hook into, fob watch, fearfulness, cold feet, fire alarm, automate, gong, chronometer, car alarm. clock, fob, disconnect, shake up, horror, alarm bell, fit out. attach, connect. chill. ground. close, fit. alarm bell
tocsin.
dread
trepidation.
frighten
petrify.
siren
buzzer.

Usage examples for alarm

  1. No one the least interested in Helen could see how things were going without serious alarm – Barren Honour: A Novel by George A. Lawrence
  2. He started, leaned back and regarded her with astonishment and some alarm – Cap'n Warren's Wards by Joseph C. Lincoln
  3. " It's the alarm he said. – The Long Lane's Turning by Hallie Erminie Rives