noun
Refers to the core or main body of a book, as opposed to supplementary sections like appendices or indexes.
この辞書の正編は約二千ページある。
The main part of this dictionary is about two thousand pages.
noun
Used for the first installment or original work in a series, contrasted with sequels or continuations.
この小説の正編は十年前に出版された。
The first book of this novel series was published ten years ago.
Compound of 正 (sei, 'correct, main') and 編 (hen, 'compilation, volume'). The spelling 篇 is a variant character for 'volume'.