What is the meaning of 東京?

Old name for 洛陽／洛阳 (Luòyáng). (especially as the Eastern Han capital, contrasted with 西京 or 長安; also used of Luoyang under Sui and Tang)

Old name for 開封／开封 (Kāifēng). (especially from the Later Jin through the Later Han, Later Zhou and Northern Song)

Old name for 慶州／庆州 (Qìngzhōu). (as Donggyeong, one of the Three Capitals (Samgyeong) of Goryeo from 987 to 1304, corresponding to present-day Gyeongju)

Old name for 遼陽／辽阳 (Liáoyáng). (as the eastern capital of the Liao and Jin dynasties)

Old name for 河內／河内 (Hénèi). (Hanoi)

Tonkin

(～都) Tokyo (a prefecture, the capital city of Japan)

an eastern capital (a capital located east of another capital, especially under a multiple-capital system)

Tokyo (a prefecture, the capital city of Japan, consisting of 23 special wards)

short for 東京都 (Tōkyō-to): the capital prefecture of Japan

short for 東京駅 (Tōkyō-eki): Tokyo Station

short for 東京府 (Tōkyō-fu): the historical Tokyo Prefecture from 1868–1943

a surname

an eastern capital

the capital of 東漢 (Tōkan, “Eastern Han”) or 後漢 (Gokan, “Later Han”), corresponds to modern Luoyang

the capital of 北宋 (Hokusō, “Northern Song”), corresponds to modern Kaifeng

the eastern capital of the Jurchen Jin dynasty, corresponds to modern Liaoyang

the capital of Yongwon province in Balhae during the Tang dynasty

dated spelling of とうきょう (Tōkyō, “Tokyo”)

Tonkin (northern region of Vietnam)

hanja form of 동경 (“alternative name of Tokyo”)

Tokyo (a prefecture, the capital city of Japan, consisting of 23 special wards)

chữ Hán form of Đông Kinh (“former name of Hanoi, Tonkin; Tokyo”)

Source: wiktionary.org