- The definition of niece is the daughter of your brother or sister, by blood or by marriage.
An example of a niece is your brother-in-law's daughter.
- the daughter of one's brother or sister
- the daughter of one's brother-in-law or sister-in-law
- an illegitimate daughter, as of a medieval prelate: a euphemism
Origin of nieceMiddle English nece ; from Old French niece ; from Late Latin neptia ; from Classical Latin neptis, granddaughter, niece, akin to nepos, nephew
Origin of nieceMiddle English nece, from Old French, from Vulgar Latin *neptia, from Latin neptis; see nepōt- in Indo-European roots.
Middle English nece (“niece, granddaughter”), from Old French nece (“niece, granddaughter”) (Modern French nièce "niece") from Vulgar Latin *neptia, representing Latin neptis (“granddaughter”), from Proto-Indo-European *nepot- (“grandchild, sister's son”). Akin to Old High German nift (“niece, granddaughter”) (German Nichte (“niece”)). Displaced native Middle English nifte (“niece, granddaughter”) (from Old English nift (“niece, granddaughter”)).