precipitation
- the action or process of precipitating a substance from a solution.
- rain, snow, sleet, or hail that falls to the ground.
- archaic,the fact or quality of acting suddenly and rashly
It's a synonymous of drop I think;
While precipitous
- dangerously high or steep:
- (of an action) done suddenly and without careful consideration:
synonyms: steep · sheer · perpendicular · abrupt · sharp · vertical
Both give me a sense of abruptly and related to the "altitude", "vertical". So, it's of pure coincidence or they have something to do with each other? Say coming from a same root? Tried but found nothing related, So I thought I'd post. Apologies if it contains grammar mistakes and wrong use of words. Feel free to edit it.