1640s, "private rooms for the use of one person within a house," from French appartement (16c.), from Italian appartimento, literally "a separated place," from appartere "to separate," from a "to" (see ad-) + parte "side, place," from Latin partem (see part (n.)). Sense of "set of private rooms in a building entirely of these" (the U.S. equivalent of British flat) is first attested 1874.
1. She went directly to Simon's apartment and knocked on the door.
2. Gerome tried to talk her into taking an apartment in Paris.
3. Stevens wrote him a note asking him to come to his apartment.
4. The high and low-rise apartment blocks built in the 1960s are crumbling.
5. It would never do to have Henry there in her apartment.