The first element possibly represents a borrowing into Latin of a pre-existing Brythonic name for the wetland area (from a word meaning reeds, cawn in Modern Welsh).

[1] Both of these etymologies would seem to reflect the purpose of building a new fort at this location, to control the lowest fording point across the river Conwy.

Canovium was a square fort built in timber at an important river crossing (at Tal-y-Cafn) by the Roman army around AD 75, possibly to house a 500-strong regiment of foot-soldiers.

[2] The fort was the largest Roman military installation in the area and it is likely that the administrative functions of the Deceangli tribe were conducted from here.

Although the tribe remained largely "un-Romanised" and no Civitas Deceangorum ever existed, the vicus at Canovium the fort may possibly have functioned as such.