lodger n: a person who occupies a rented room in another's house
: a person who by agreement with the owner of a house acquires no property, interest, or possession therein but only the right to occupy a designated room or area that remains in the owner's legal possession
Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.