- 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.
niece definition by Webster's New World
- 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: Middle English nece ; from Old French niece ; from Late Latin neptia ; from Classical Latin neptis, granddaughter, niece, akin to nepos, nephew
niece definition by American Heritage Dictionary
- The daughter of one's brother or sister or of the brother or sister of one's spouse.
- The illegitimate daughter of an ecclesiastic who has taken a vow of celibacy.
Origin: Middle English nece, from Old French, from Vulgar Latin *neptia, from Latin neptis; see nepōt- in Indo-European roots.