AIR n.
A musical idea, or motive, rhythmically developed in consecutive single tones, so as to form a symmetrical and balanced whole, which may be sung by a single voice to the stanzas of a hymn or song, or even to plain prose, or played upon an instrument; a melody; a tune; an aria.
ALARM n.
A mechanical contrivance for awaking persons from sleep, or rousing their attention; an alarum. Alarm bell, a bell that gives notice on danger. -- Alarm clock or watch, a clock or watch which can be so set as to ring or strike loudly at a prearranged hour, to wake from sleep, or excite attention. -- Alarm gauge, a co…