plummet
n.n. a very fast and sudden drop in something, like a price or a temperature. It is a more formal word than 'fall' or 'drop'.
n. a sudden and steep descent or decline in value, level, or intensity. Often used in financial or meteorological contexts to describe a rapid change.
The price of oil took a sharp plummet last week.
After the news of the merger, the company's stock took a dramatic plummet, losing nearly half its value in a single day.
The sudden plummet in global temperatures during the winter months forced the agricultural sector to reconsider its planting schedules for the following season.
From Middle English plommet (“ball of lead, plumb of a bob-line”), recorded since 1382, from Old French plommet or plomet, the diminutive of plom, plum (“lead, sounding lead”), from Latin plumbum (“lead”). The verb is first recorded in 1626, originally meaning “to fathom, take soundings", from the noun.