noun
addendum; annex; appendix; subsidiary clause
Used in legal and formal documents for supplementary clauses or attachments to a main text.
契約書の副文に、解約条件が詳しく書かれている。
The cancellation conditions are detailed in the addendum to the contract.
noun
Grammar term for a clause that depends on a main clause; often contrasted with 主文 (main clause).
この文では、副文が主文の内容を補足している。
In this sentence, the subordinate clause supplements the content of the main clause.
Compound of 副 (sub-, auxiliary) and 文 (sentence, text). The exact historical derivation is uncertain, but the word follows standard Sino-Japanese word formation.