mainstem

English

Etymology

From main +‎ stem.

Noun

mainstem (plural mainstems)

1. The principal watercourse of a river that has multiple streams
   • 2015 July 9, “Diverse Early Life-History Strategies in Migratory Amazonian Catfish: Implications for Conservation and Management”, in PLOS ONE‎, →DOI:

     Piramutaba (Brachyplatystoma vaillantii) make up a second large export fishery and are found almost exclusively in the Amazon River mainstem, whitewater tributaries, and the estuary [30 –32 ].