written oath; pledge; covenant
A formal written document in which one swears or promises to do something. Often used in legal, business, or official contexts.
I submitted a written pledge of confidentiality when I joined the company.
Before the contract, both parties need to sign a written covenant.
誓約書 is a written pledge or oath (often one-sided), while 契約書 is a mutual contract between two or more parties.
Compound of 誓約 (pledge, oath) and 書 (document).