Tokyo was originally known as Edo, meaning estuary. Its name was changed to Tokyo (Tōkyō: tō (east) + kyō (capital)) when it became the imperial capital in 1868. During the early Meiji period, the city was also called "Tōkei", an alternative pronunciation for the same Chinese characters representing "Tokyo". Some surviving official English documents use the spelling "Tokei", however this pronunciation is now obsolete.