precipitously
adverb /prɪˈsɪpɪtəsli/
  /prɪˈsɪpɪtəsli/
(formal)- in a way that is very steep, high and often dangerous- The land dropped precipitously down to the rocky shore.
 
- suddenly and to a very great extent- The dollar plunged precipitously.
 
- very quickly, and without enough thought or care synonym hastily (2)- We don't want to act precipitously.