Unencumbered or unrestricted legal ownership that is free from doubt as to its validity.
The phrase implies that ownership is not subject to claims by anyone but the person holding title. It is also called marketable title, or title that can be easily transferred or sold because of its lack of encumbrances.
n. holding ownership of real property without any claims by others on the owner's title and no history of past claims which might affect the ownership. (See: cloud on title)