tributary [tributaries]◼◼◼(stream which flows into a larger one) noun [UK: ˈtrɪ.bjʊ.tə.ri] [US: ˈtrɪ.bjə.ˌte.ri]The Amazon is fed by a large number of tributaries. = L'Amazone a un grand nombre d'affluents.
branch [branches]◼◼◻(creek or stream which flows into a larger river) noun [UK: brɑːntʃ] [US: ˈbræntʃ]