GNU Collaborative International Dictionary of English

Found one definition

1.       
   Apartment house. A building comprising a number of lving units (apartments4) designed for separate housekeeping tenements, but having conveniences, such as heat, light, elevator service, etc., furnished in common; contrasted to a detached dwelling.  Sometimes distinguished in the United States from a flat house, in which each living unit comprises one entire floor, whereas in an apartment house a floor may be partitioned into any number of apartments4.
   
   [Webster 1913 Suppl. +PJC]