सतही अथवा भूमिगत सरिता जो लगातार या आन्तरिक रूप से दूसरी बड़ी नदी में जल डालती है।
Tributary: A tributary is generally regarded as a surface water drainage system which is interconnected with a river system. Under Colorado law, all surface and groundwater, the withdrawal of which would affect the rate or direction of flow of a surface stream within 100 years, is considered to be tributary to a natural stream.