\Rap"id-fire`\, Rapid-firing \Rap"id-fir`ing\, a.
(a) (Gun.) Firing shots in rapid succession.
(b) (Ordnance) Capable of being fired rapidly; -- applied to
    single-barreled guns of greater caliber than small arms,
    mounted so as to be quickly trained and elevated, with a
    quick-acting breech mechanism operated by a single motion
    of a crank or lever (abbr. R. F.); specif.: (1) In the
    United States navy, designating such a gun using fixed
    ammunition or metallic cartridge cases; -- distinguished
    from breech-loading (abbr. B. L.), applied to all guns
    loading with the charge in bags, and formerly from
    quick-fire. Rapid-fire guns in the navy also sometimes
    include automatic or semiautomatic rapid-fire guns; the
    former being automatic guns of not less than one inch
    caliber, firing a shell of not less than one pound
    weight, the explosion of each cartridge operating the
    mechanism for ejecting the empty shell, loading, and
    firing the next shot, the latter being guns that require
    one operation of the hand at each discharge, to load the
    gun. (2) In the United States army, designating such a
    gun, whether using fixed or separate ammunition, designed
    chiefly for use in coast batteries against torpedo
    vessels and the lightly armored batteries or other war
    vessels and for the protection of defensive mine fields;
    -- not distinguished from quick-fire. (3) In Great
    Britain and Europe used, rarely, as synonymous with
    quick-fire.