ˈflüvēəl, -vyəl adjective
Etymology: Latin fluvialis, from fluvius river (from fluere to flow) + -alis -al — more at fluid
1.
a. : of or relating to rivers
fluvial law
b. : conforming to the changing course of a stream
a fluvial boundary
2. : growing or living in streams
fluvial vegetation
3. : produced by river action
a fluvial plain