condominium The absolute ownership of an apartment or a unit, generally in a multiunit building, based on a legal description of the airspace that the unit actually occupies, plus an undivided interest in the ownership of the common elements that are owned jointly with the other condominium unit owners. The entire tract of real estate included in a condominium development is called a parcel, or development parcel. One apartment or space in a condominium building, or a part of a property intended for independent use and having lawful access to a public way is called a unit. Ownership of one unit also includes a definite undivided interest in the common elements.