Tributary (noun)

1. A river or stream flowing into a larger river or a lake.
2. A smaller or secondary stream that flows into a larger river.
3. A person, group, or state that pays tribute to a more powerful person, group, or state.

Origin:

Late middle english: from old french tributaire, from latin tributarius, from tributum "tribute".

Examples:

1. The Mississippi River has numerous tributaries that flow into it from different regions.
2. The tributary stream flowed gently into the larger river.
3. In ancient times, many countries were tributaries of the Roman Empire, paying taxes and tribute to the emperor.
4. The kingdom was forced to become a tributary of the more powerful neighboring empire.
5. The small tribe was a tributary to the larger and more powerful neighboring tribe.