Flowing out; emanating.n. That which flows out or issues forth.n. Specifically, in geography, a stream that flows out of another stream or out of a lake: as, the Atchafalaya is an effluent of the Mississippi river.n. In mathematics, a covariant of a quantic of degree mn in i variables, the covariant being of degree m and in p variables, where p is the number of permutations that can be obtained by dividing n into i parts.