plunge-n; 2 Senses

Sense Number 1: dive, dunk or rapid swim through water

Commentary: PLUNGE[+action][+immersion][+brief][+water]

We decided to take a plunge in the cool mountain lake.
Jane took the cold plunge after the Roman bath at the spa.
A plunge in the pool each morning before breakfast always clears my mind.

PropBank: plunge.02
WordNet 3.0 Sense Numbers: 1

Sense Number 2: a sharp or rapid descent

Commentary: PLUNGE[+action][+descent][+rapid]
NOTE: usually implies a quantitative change

The stock market experienced a 30 percent plunge on black Monday.
The aircraft made a plunge when it hit a strong downdraft at 30,000 feet.
The country was devastated by the plunge in its currency in the world markets.
John was baffled by his sudden plunge into depression. (figurative)

PropBank: plunge.01
WordNet 3.0 Sense Numbers: 2