:to place (someone) in a new office or position by having an official ceremony in which that person makes a formal promise to do the work properly, to be honest and loyal, etc.使宣誓就职
When do they swear him in?他们什么时候让他宣誓就职?
— often used as (be) sworn in常用作(be) sworn in
The new president will be sworn in tomorrow.新总统明天宣誓就职。