a·larm / əˈlärm/ • n. an anxious awareness of danger: the boat tilted and the boatmen cried out in alarm he views the right-wing upsurge with alarm. ∎  [in sing.] a warning of danger: I hammered on doors to raise the alarm. ∎  a warning sound or device: a burglar alarm. ∎  an alarm clock.• v. 1. [tr.] cause (someone) to feel frightened, disturbed, or in danger: the government was alarmed by an outbreak of unrest.2. (be alarmed) be fitted or protected with an alarm: this door is locked and alarmed between 11 p.m. and 6 a.m.DERIVATIVES: a·larm·ing·ly adv.ORIGIN: late Middle English (as an exclamation meaning ‘to arms!’): from Old French alarme, from Italian allarme, from all' arme! ‘to arms!’

alarm †(excl.) to arms! XIV; call to arms, †surprise attack; state of surprise with fear XVI. ME. alarme, alarom, later alarum (XVI) — (O)F. alarme — It. allarme, i.e. all'arme ‘to the arms’ (see ARM2), orig. a call.
Hence alarm vb. XVI.