Plummet is a verb that means "to fall straight down" or "to become much less." The verb can be used literally or figuratively.
The company's sales have plummeted this year.
A strange object plummetedto the earth from the night sky.
The number of full-time jobs has plummetedsince the economy crashed.
As a noun, a plummet is a tool used to see if something is completely vertical or to measure depth. This tool is also referred to as a "plumb," "plumb bob," or "plumb line" and consists of a weight attached to a line or string. If you want to see how deep a body of water is, you might use a plummet to test this.
Plummet is a strong-sounding word that is often used in news headlines, especially for articles about stocks or statistics. For example, some recent headlines using this word are "European Stocks Fall as Chinese Imports Plummet" (TheStreet) and "US Goods Exports Plummet as Dollar Rises, Commodity Prices Fall" (The Wall Street Journal).
From Middle French "plomb" (lead); first appeared as "plommet" in Middle English 1350–1400.