1. past tense of plunge; to jump or dive quickly and forcefully into water or downward
2. past tense of plunge; to fall or drop suddenly and steeply
3. past tense of plunge; to thrust or push something quickly and forcefully into something else

Examples

• She plunged into the cold lake without hesitation.
• The stock market plunged after the announcement.
• He plunged the knife into the watermelon.
• The room plunged into darkness when the power went out.
• She plunged into her new job with enthusiasm.
• The car plunged off the cliff into the valley below.
• He plunged his hand into the bag of coins.