precipitant
Inclined to make rapid decisions without due consideration; hasty, impulsive, rash.
Of a fall: straight downwards; headlong.
(figurative) Acting, happening, or moving quickly; fast, rapid, swift; also, abrupt, sudden, unexpected.
(chemistry) That causes (t=formation of a heavier solid in a lighter liquid as a result of a chemical reaction).
(archaic) (t=in a precipitant or headlong manner; with foolish or rash haste)
Something which causes or hastens the occurrence of an act or event; specifically (psychology), something which brings about a mental or physiological condition.
(chemistry) A substance that, when added to a solution, causes a dissolved substance to form a precipitate.