1. noun /əˈlɑːm,əˈlɑɹm/
Arming to answer in a night alarm. Shakespeare.
b) Any sound or information intended to give notice of approaching danger; a warning sound to arouse attention; a warning of danger.
Sound an alarm in my holy mountain. Joel ii. 1.
2. verb /əˈlɑːm,əˈlɑɹm/
a) To call to arms for defense
Wikipedia foundation.