The Collaborative International Dictionary of English v.0.48:
Distributary \Dis*trib"u*ta*ry\, a. Tending to distribute or be distributed; that distributes; distributive. [1913 Webster]WordNet (r) 3.0 (2006):
distributary n 1: a branch of a river that flows away from the main stream and does not rejoin it [ant: affluent, confluent, feeder, tributary]