Learn how to pronounce ‘mouth’ and the suffix ‘-mouth’ in a British RP accent! 🇬🇧🔍 Learn about the difference. Can you catch the difference? Then learn about the what a mouth of the river is. From Wikipedia:A river mouth is where a river flows into a larger body of water, such as another river, a lake/reservoir, a bay/gulf, a sea, or an ocean.So, normally a town or city with the suffix ‘-mouth’ lies on the mouth of a river. So, Yarmouth is located at the mouth of the river Yar on Isle of Wigh