Plunge, v. i.
 1. To thrust or cast one's self into water or other fluid; to submerge one's self; to dive, or to rush in; as, he plunged into the river. Also used figuratively; as, to plunge into debt.
    Forced to plunge naked in the raging sea.   --Dryden.
    To plunge into guilt of a murther.   --Tillotson.
 2. To pitch or throw one's self headlong or violently forward, as a horse does.
    Some wild colt, which . . . flings and plunges.   --Bp. Hall.
 3. To bet heavily and with seeming recklessness on a race, or other contest; in an extended sense, to risk large sums in hazardous speculations. [Cant]
 Plunging fire Gun., firing directed upon an enemy from an elevated position.