written petition; memorial
A formal document submitted to an authority, such as a government or organization, to state an opinion or make a request. Often used in historical or political contexts.
彼らは政府に建白書を提出した。
They submitted a written petition to the government.
Compound of 建白 (opinion stated to a superior) and 書 (document). The exact historical derivation is uncertain, but the term is conventionally associated with formal written appeals.