Well, when all else fails, refer to the regulations:
Improved property loan means an extension of credit secured by one of the following types of real property:
(1) Farmland, ranchland or timberland committed to ongoing management and agricultural production;
(2) 1- to 4-family residential property that is not owner-occupied;
(3) Residential property containing five or more individual dwelling units;
(4) Completed commercial property; or
(5) Other income-producing property that has been completed and is available for occupancy and use, except income-producing owner-occupied 1- to 4-family residential property.