associative

adjective

1. 1

   Pertaining to, resulting from, or characterised by association; capable of associating; tending to associate or unite.

2. 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. 3

   Addressable by a key more complex than an integer index.

   “AWK's associative arrays may be indexed by strings.”