Among the names of ancient Celtic regions we have Abrin-catui, that is (without any change in the word) Aber-In-Catui; the name of a Tribe in Normandy, about Avranches, which is at the mouth of a River now called the See. (Another stream flows into the same Estuary.)
Aber—In—Cattui.
Literally,
“Estuary (of the) River—Tribes or People,” i.e. The Tribes living at the Estuary of the River or Rivers.
The name of the same place will also furnish an example of a corresponding term, primarily meaning “The Mouth,” in the modern Celtic.
Genœ (Welsh), Ganau (Cornish), Gion (Irish), Genu (Armorican), mean “The Mouth.”
The original name of “Avranches,” when the country was first subdued by the Romans, was In-“gena.” Here it is plain “Gena” was synonymous with Aber! The Town was afterwards called Aber-in-Catui by the Romans, who very generally gave the names of the Celtic tribes to their principal Towns.
In D'Anville's Map we find, in the same part of Gaul, Aræ-genu-s given to Bayeux, (the capital of the Bajocasses,) at the mouth of a river now called the “Ayr!”
The following are very striking examples of the occurrence of the same word, Genœ or Ganau: