Although there are many theories on the etymology of the Edo as a place name, the theory that the Character "e" [江] refers to a river or mouth of a river, and "to" [戸] as a gate or theshhold and hence "entry to a river" has been widely accepted.
地名の語源は諸説あるが、江は川あるいは入江とすると、戸は入口を意味するから「江の入り口」に由来したと考える説が有力である。