The phrase "precipitous decline" means a sudden and steep decrease in something, typically referring to a significant drop or fall in a short period of time. Full definition
Some apps, such as Facebook and its adjunct Messenger, saw precipitous declines over that time, while only Snapchat and Uber had modest increases in total downloads. (canadianbusiness.com)
But the economy has been in precipitous decline since Mr. Maduro succeeded Hugo Chávez in 2013. (nytimes.com)
Which is why projections for precipitous declines in the price of batteries — as much as 40 — 60 percent over the next five years according to one recent report — are such good news. (climaterealityproject.org)