Definitions of swearing in
the action of making someone take an oath (=a promise that that a person will tell the truth) as a witness (=someone who tells a court what they know about something that has happened) in a court
The trial begins with the formal calling and swearing in of the witnesses to initiate the trial proceedings.
the action of making someone take an oath (=a promise to act a certain way in the future) to act in an official capacity
This is for the first time that heads of the states of Saarc nations have been invited to attend the swearing-in ceremony of the Prime Minister.