means To cause something to happen suddenly or prematurely, or — in chemistry — to make a dissolved substance separate out as a solid; as an adjective, it means rash and hasty.

from From Latin praecipitare, "to throw headlong," built from prae- "before, forward" and caput "head" — literally to send something off head-first over a cliff. That cliff-edge sense survives in "precipice," a close cousin sharing the same plummeting root. The chemical meaning is younger and gentler, picturing a substance "falling out" of its solution, while the everyday sense keeps the original reckless tumble: to precipitate a crisis is to push it over the edge.