[Latin literal translation: for the suit]
A guardian ad litem is a guardian (usually a lawyer) appointed by the court to manage the affairs of the ward as they relate to a proceeding or particular aspect of litigation, as opposed to a guardian, who would have all legal responsibilities.
An attorney ad litem is a court-appointed lawyer who represents a child during the course of a legal action, such as a divorce, termination, or child-abuse case. The attorney owes to the child the duties of loyalty, confidentiality, and competent representation.
An administrator ad litem is appointed by the court of probate to represent an estate during a lawsuit when an estate of a deceased person must be represented. An administrator ad litem is appointed only if there is no existing executor or administrator of the estate, or if the executor or administrator has conflicting interests.