indenture
🇺🇸
/ɪnˈdentʃər/
🇬🇧
/ɪnˈdentʃə(r)/
A legal agreement in which someone agrees to work for someone else for a certain period of time, often without pay, in exchange for something like training or passage to a new country.
He was bound by an indenture to his master for four years.