plummet - fall
If something were to ‘plummet’, it would drop or decrease rapidly and by a large amount. It can be used in a literal and figurative sense, but it is important to note that figuratively the term differs from similar meaning words like ‘decline’ in that the sharp drop being expressed is often temporary in nature. Most commonly encountered in a professional context.
I watched the large boulder come off the side of the mountain and plummet to the road below. It’s lucky there were no cars passing when it happened!
When the takeover of that company fell through, their stock price plummeted. It is expected to recover once a new bid is made.
That politician’s popularity has been plummeting in recent weeks due to sordid newspaper revelations about his private life.