Noun

• S: (n) feeder, tributary, confluent, affluent (a branch that flows into the main stream)

Adjective

• S: (adj) tributary ((of a stream) flowing into a larger stream)
• S: (adj) tributary (paying tribute) "a tributary colony"
• similar to
• S: (adj) obligated (caused by law or conscience to follow a certain course) "felt obligated to repay the kindness"; "was obligated to pay off the student loan"
• antonym
• W: (adj) unobligated [Indirect via obligated] (not obligated)
• S: (adj) conducive, contributing, contributive, contributory, tributary (tending to bring about; being partly responsible for) "working conditions are not conducive to productivity"; "the seaport was a contributing factor in the growth of the city"; "a contributory factor"