A concord negindefinite is a pronoun (or determiner) which can occur in a negative concord construction in the scope of the negation meaning.
The term is from Haspelmath (2025: 62). Concord negindefinites have often been called "n-words" (or N-words) (following Laka 1990: 108), but the precise meaning of "n-word" (or more recently, "negword") has been unclear since the beginning.