precipitant
/prɪˈsɪpɪt(ə)nt/adj
University
1
Inclined to make rapid decisions without due consideration; hasty, impulsive, rash.
2
Of a fall: straight downwards; headlong.
3
Acting, happening, or moving quickly; fast, rapid, swift; also, abrupt, sudden, unexpected.
4
That causes precipitation (“formation of a heavier solid in a lighter liquid as a result of a chemical reaction”).