ex relatione prep[Medieval Latin]
: by or on the relation or information of NOTE: The abbreviation for ex relatione ex rel., is used in the title of informations and special proceedings to designate the interested individual, called the relator, at whose instance the state or public officer is acting.
Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.