tributary (adj.)

late 14c., "paying tribute," from Latin tributarius "liable to tax or tribute," from tributum (see tribute).

late 14c., "person, country, etc. owing obedience or paying tribute or a tax to a sovereign or another people," from Latin tributarius (see tributary (adj.)). Meaning "stream that flows into a larger body" is from 1822, from the adjective in this sense, which is recorded from 1610s.