noun
Legal term for a sworn written statement or testimony recorded outside of court. Used in formal legal contexts.
裁判所に口供書を提出した。
I submitted an affidavit to the court.
証人の口供書が証
The witness's deposition was admitted as evidence.
Compound of 口 (oral) + 供 (statement) + 書 (document), literally 'oral statement document'. The exact historical derivation is uncertain, but the term is conventionally used in legal contexts.