indenture
verb [ T ] uk/ɪnˈden.tʃər/ us/ɪnˈden.tʃɚ/
签订契约（尤指做学徒）
(in the past) to officially agree that someone, often a young person, will work for someone else, especially in order to learn a job
He was indentured to a carpenter. 他签订契约成了木匠的学徒。
The land was worked on by indentured servants. 这块土地是由契约工人耕种的。