tributary

(noun) a branch that flows into the main stream. Synonyms: feeder, confluent, affluent.

(adj) (of a stream) flowing into a larger stream.

(adj) paying tribute. Example: "A tributary colony."

(adj) tending to bring about; being partly responsible for. Synonyms: conducive, contributing(prenominal), contributive, contributory. Examples: "Working conditions are not conducive to productivity." "The seaport was a contributing factor in the growth of the city." "A contributory factor."