出典:Wiktionary
Sinologists distinguish between the language as used in antiquity (Classical Chinese), and the language used after the fall of the Han Dynasty (Literary Chinese), similar to the distinction between Classical Latin and Late Latin. In casual usage, these may be conflated.
This should not be confused with the literary register of Modern Chinese, meaning “modern Chinese words that are only used in writing”, or with archaic terms in Modern Chinese. (In the Pinyin Chinese-English dictionary, these usage notes are indicated by <书 (shū)> and <旧 (jiù)>, respectively.)