The definition from wikipedia seems correct and general enough:
collection of unique keys and a collection of values, where each key is associated with one value (or set of values)
Not a word about order. That should be perfectly fine, as there are many good ways to implement data structures that are perfect associative arrays, only without the "ordered" requirement (if it was there). I've never heard someone claim a "tree map" (as some APIs call it because it internally uses a balanced binary tree) or hashtable isn't an associative array because it's ordered or not. Plus, most code doesn't care if the keys are ordered.
And even if you managed to find a reputable source defining associative arrays to be ordered, there's plenty of people and text out there that doesn't go on that assumption. To be safe, you should explicitly add the "ordered" requirement when it matters and omit it whenever it doesn't matter (which is surprisingly often).