A precipitous action happens very quickly and often without being planned. a precipitous decision. + precipitously pre·cipi·tous·ly They've got to act precipitously to make the deals
done with very great haste and without due deliberation; "hasty marriage seldom proveth well"- Shakespeare; "hasty makeshifts take the place of planning"- Arthur Geddes; "rejected what was regarded as an overhasty plan for reconversion"; "wondered whether they had been rather precipitate in deposing the king"
A precipitous slope or drop is very steep and often dangerous. The town is perched on the edge of a steep, precipitous cliff. + precipitously pre·cipi·tous·ly The ground beyond the road fell away precipitously
A precipitous change is sudden and unpleasant. The stock market's precipitous drop frightened foreign investors + precipitously pre·cipi·tous·ly The company has seen its profits fall precipitously over the past few years