drainage basin

WordReference Random House Unabridged Dictionary of American English © 2026

drain′age ba′sin, 

1. Geography, Geology the area drained by a river and all its tributaries. Also called catchment area, drain′age ar′ea. Cf. watershed (def. 2).

• 1880–85, American.

Collins Concise English Dictionary © HarperCollins Publishers::

drainage basin, drainage area noun

1. another name for catchment area