early 16th century: from Latin praecipitat- 'thrown headlong', from the verb praecipitare, from praeceps, praecip(it)- 'headlong', from prae 'before' + caput 'head'. The original sense of the verb was 'hurl down, send violently'; hence 'cause to move rapidly', which gave rise to sense 1 (early 17th century)
The adjectives precipitate and precipitous are sometimes confused. Precipitate means ‘sudden, hasty’: a precipitate decision the fugitive’s precipitate flight. Precipitous means ‘steep’: the precipitous slope of the mountain a precipitous decline in stock prices.