Sentence:  He had assumed that all these buildings had been divided into <WSD>apartments</WSD> , but this one , from a glance at the hall furnishings , was obviously still a functioning town house , and its owners were in residence ; that made it doubtful as the hiding place of a man whose plans had to be made in advance . 
Meaning of the word marked with <WSD> tags:  a suite of rooms usually on one floor of an apartment house