Ouchi (Imperial Palace) - Ouchi

Japanese: 大内（皇居） - おおうち

…the residence of the Emperor. In the past, it was called Miya, Miyashitsu, Dairi, Kinri, Kinchu, Kinkaku, Uchi, Gosho, and other honorific names such as Omiya, Ouchi, Kokonoe, and Momoshiki, and the term "Imperial Palace" also appeared in records during the Heian period. When the capital was moved to Tokyo, Edo Castle was renamed Tokyo Castle, and then officially called the Imperial Palace, but after the Meiji Palace was completed, the official name was Miyagi.

From 【The Imperial Palace】

…It refers to the central part of the palace of an ancient capital city, the place where the emperor lived. It was also called "Ouchi" or "Uchi." In the Heian Palace, it had an area measuring 100 jo (about 303 m) from north to south and 70 jo (about 212 m) from east to west, and was divided into the northern half, the inner palace, and the southern half, the emperor's permanent residence, which were separated by a tile fence (Figure).

*Some of the terminology that refers to "Ouchi (Imperial Palace)" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…天皇の住居。古くは宮，宮室，内裏，禁裏，禁中，禁闕，内，御所などのほか，大宮，大内，九重，百敷（ももしき）などの美称もあり，〈皇居〉の語も平安時代には記録に見える。東京遷都に際し，江戸城を東京城と改称，ついで皇城と公称したが，明治宮殿完成後は宮城を公称と定めた。…