mainstem

The principal watercourse of a river that has multiple streams

Noun

  1. The principal watercourse of a river that has multiple streams
    • 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 ]. - 2015 July 9, “Diverse...

Origin

From main + stem.

Forms

mainstems