Plunge (verb)

1. To move quickly and suddenly forward or downward.
2. To cause to suddenly enter a particular state or condition.
3. To cause to move quickly and suddenly forward or downward.

Origin:

Mid 16th century: from latin plongere, from plumbum "lead" (because the lead weight on a plumb line was used to measure depths).

Examples:

1. He plunged into the pool.
2. She plunged the knife into the cake.
3. The stock market plunged.
4. He plunged the company into debt.
5. She plunged into the ocean.