1
always followed by an adverb or preposition : to fall or jump suddenly from a high place
Her car plunged off a bridge.
He plunged [=dove] into the pool.
The rocket plunged [=plummeted] toward the Earth.
The parachute failed to open, and the jumper plunged to her death. [=died from her fall]
2
: to fall or drop suddenly in amount, value, etc. : plummet
The stock market plunged yesterday.
The President's approval rating has plunged to 20 percent.
The moose population has plunged in recent years.
3
always followed by an adverb or preposition : to have a steep slope or drop downward
The rocky cliffs plunge into the swirling rapids below.
The road plunges down the mountain.
: a sudden fall or jump usually from a high place
Amazingly, the cat survived its plunge from the building's roof.
2
: a sudden quick fall in amount, value, etc.
Market analysts predicted a price plunge.
The store experienced a sharp plunge in sales.
3
: the act of suddenly beginning to be in a particular condition or situation — usually + into
his plunge into severe depression
A series of bad management decisions are responsible for the company's plunge into debt.