To enlist oneself (in something) or become a member (of something)
To enter (a name, etc.) in a register, roll or list
To enlist (someone) or make (someone) a member of
To bring in as a member; to make a part of.
To draft into military service.
To formally or ceremoniously install in an office, position, etc.
To introduce into (particularly if certain knowledge or experience is required, such as ritual adulthood or cults).