associative

adjective

1. Pertaining to, resulting from, or characterised by association; capable of associating; tending to associate or unite.
2. (of a binary operator *) Such that, for any operands a, b and c, (a * b) * c = a * (b * c); (of a ring, etc.) whose multiplication operation is associative.
3. Addressable by a key more complex than an integer index.“AWK's associative arrays may be indexed by strings.”