accessory apartment

noun, US

Definition of accessory apartment

: a rental unit that is located on the lot of or within a single-family owner-occupied home In 1991, the town moved away from an almost exclusive reliance on single-family homes and passed a law that began a process of legalizing some of Huntington's thousands of illegal accessory apartments.Newsday, 14 Sept. 2010

First Known Use of accessory apartment

1973, in the meaning defined above

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