noun
A jet or current of water or vapour directed upon some part of the body to benefit it medicinally; in particular, such a jet directed at the vagina for irrigation.
Something that produces the jet or current in the previous sense, such as a syringe.
(obsolete) A jet or spray of any liquid.
(slang, humorous, vulgar) Ellipsis of douchebag (“objectionable person”).
verb
(transitive) To administer a douche to; to shower; to douse
(intransitive) To use a douche.