4. (noun)river basin, basin, watershed, drainage basin, catchment area, catchment basin, drainage area the entire geographical area drained by a river and its tributaries; an area characterized by all runoffbeing conveyed to the sameoutlet "flood control in the Missouri basin"
5. (noun)washbasin, basin, washbowl, washstand, lavatory a bathroomsink that is permanently installed and connected to a watersupply and drainpipe; where you can wash your hands and face "he ran some water in the basin and splashed it on his face"