vacancy (n.)
1570s, "a vacating;" c.1600, "state of being vacant," from Late Latin vacantia, from Latin vacans "empty, unoccupied," present participle of vacare "be empty" (see vain). From 1690s as "a vacant office or post;" meaning "available room at a hotel" is recorded from 1953. Related: Vacance (1530s); vacancies.