ancient language; ancient word
General term for words or language from ancient times, not limited to Japanese.
Research on ancient languages is difficult because there are few documents.
Old Japanese
In linguistics, specifically refers to the Japanese language from the late 6th century to the end of the Nara period.
Old Japanese as an ancient language can be seen in works like the Man'yōshū.
A broader term for ancient language, not specifically the Old Japanese period.
Compound of 上代 (jōdai, 'ancient times') + 語 (go, 'language').