I want to say that complexity is an emergent — and, as such, unfixed — multiplicity that is not a chaos. Complexity is always on the cusp of order.
The univocal cannot be complex. However, one note or one tone that endured just so and reverberated just so might be complex in that it forges multiplicity in its singular wake.
As necessarily a multiplicity, complexity entails a quantification — not one voice but many voices.
But this "many" is not really a more as much as it's a differentiation (or is it differenciation? Tell me, all you mathematicians).
Complexity is a quality — the quality of multiple trajectories that don't unify or stay fixed and yet is not a chaos.
Complexity is not complicated. Nor is it convoluted.
This post, however, may be.