precipitous adj.

late 15c., precipitacioun, "a casting down" (of the evil angels from heaven), also, in alchemy "separation of a solid substance from a solution," from Old French precipitation (15c.) and directly from Latin praecipitationem (nominative praecipitatio) "act or fact of falling headlong, haste," noun of action from past-participle stem of praecipitare "to throw or dive headlong; be hasty," from praeceps (genitive praecipitis) "steep, headlong, headfirst," from prae "before, forth" (see pre-) + caput "head" (from PIE root *kaput- "head").

The meaning "sudden haste" is from c. 1500. The meaning "act of falling from a height" is attested from 1610s. The meteorological sense of "rain, snow, dew, frost, hail, etc.; moisture from the atmosphere deposited on the earth's surface" is from 1670s.

1610s, now obsolete, but formerly preferred by purists for the sense "high and steep" over the later formation precipitous. Related: Precipitiously.