誓せい書しょせいしょMeanings1nounwritten oath; written pledgeA formal document in which one swears or promises something in writing. Similar to 誓約書 (せいやくしょ), but 誓書 is less common and may appear in legal or solemn contexts.See also: 誓約書彼かれは裁さい判ばん所しょに誓せい書しょを提てい出しゅつした。