Definition of plunges:
(v) :
(intransitive) To dive, leap or rush (into water or some liquid); to submerge oneself.
(v) :
(transitive) To thrust into liquid, or into any penetrable substance; to immerse.
(v) :
(figuratively, transitive) To cast, stab or throw deep and fast into some thing, state, condition or action.
(v) :
(figuratively, intransitive) To fall or rush headlong into some thing, action, state or condition.
(v) :
(intransitive) To pitch or throw oneself headlong or violently forward, as a horse does.
(n) :
The act of plunging or submerging.