Mainstem

noun

noun ·Rare ·Advanced level

Definitions

Noun
  1. 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 ]."

Example

More examples

"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 ]."

Etymology

From main + stem.

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.