Dinn is an English and Irish surname, of Gaelic or Norman origin. The name has three possible origins, a nickname for Dennis (Dinis), another origin is an Irish Byname meaning Brown or Dark coloured, another origin is Anglo-Norman meaning an inhabitance of the Norman town Dives-sur-Mer. The surname is well known in the United States and Canada. The surname is very common in Massachusetts and Indiana in the United States, and in Canada the surname is very common in Newfoundland and Labrador.