Does the suffix '-mouth' in a place name refer to the mouth of a river, as in Plymouth, Dartmouth, et al?

Tabby Tom

Plymouth and Dartmouth are certainly so called because they're at the mouths of the rivers Plym and Dart. Similarly Tynemouth is at the mouth of the Tyne and Falmouth at the mouth of the Fal. But there may be one or two names which are derived differently. May 07 02, 4:57 AM

mk2norwich

A few miles from my hometown is a place called Yarmouth, which is at the mouth of the river Yare. May 07 02, 10:53 AM

fpgjc

place name is formed from the Celtic river name + OE mutha Yarmouth IoW from 'Ernemuth' gravelly or muddy estuary Yarmouth Norfolk from Mouth of River Yare Dictionary of English Place Names ( Can be found in Past-Times shops) May 07 02, 1:11 PM