Webster's Revised Unabridged Dictionary · 1913

Plunge

Plunge , transitive verb

[Old English ploungen, Old French plongier, French plonger, from (assumed) Late Latin plumbicare, from Latin plumbum lead. See Plumb.]

1.
To thrust into water, or into any substance that is penetrable; to immerse; to cause to penetrate or enter quickly and forcibly; to thrust; as, to plunge the body into water; to plunge a dagger into the breast. Also used figuratively; as, to plunge a nation into war.
To plunge the boy in pleasing sleep. — Dryden
Bound and plunged him into a cell. — Tennyson
We shall be plunged into perpetual errors. — I. Watts
2.
To baptize by immersion.
3.
To entangle; to embarrass; to overcome. [Obsolete]
Plunged and graveled with three lines of Seneca. — Sir T. Browne

Plunge , intransitive verb

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]
Collocations (1)
Plunging fire (Gunnery) , firing directed upon an enemy from an elevated position.

Plunge , noun

1.
The act of thrusting into or submerging; a dive, leap, rush, or pitch into, or as into, water; as, to take the water with a plunge.
2.
Hence, a desperate hazard or act; a state of being submerged or overwhelmed with difficulties. [Rare]
She was brought to that plunge, to conceal her husband's murder or accuse her son. — Sir P. Sidney
And with thou not reach out a friendly arm, To raise me from amidst this plunge of sorrows? — Addison
3.
The act of pitching or throwing one's self headlong or violently forward, like an unruly horse.
4.
Heavy and reckless betting in horse racing; hazardous speculation. [Cant]
Collocations (2)
Plunge bath , an immersion by plunging; also, a large bath in which the bather can wholly immerse himself.
Plunge battery or plunging battery (Electricity) , a voltaic battery so arranged that the plates can be plunged into, or withdrawn from, the exciting liquid at pleasure.