c. 1300, from Old French niece "niece, granddaughter" (12c., Modern French nièce), earlier niepce, from Latin neptia (also source of Portuguese neta, Spanish nieta), a more decidedly feminine form of neptis "granddaughter," in Late Latin "niece," fem. of nepos "grandson, nephew" (see nephew). Replaced Old English nift, from Proto-Germanic *neftiz, from the same PIE root (Old English also used broðordohter and nefene).
Until c. 1600, it also commonly meant "a granddaughter" or any remote female descendant. Cognate with Spanish nieta, Old Lithuanian neptė, Sanskrit naptih "granddaughter;" Czech net, Old Irish necht, Welsh nith, German Nichte "niece."