Accompaniment

That which accompanies; something that attends as a circumstance, or which is added to give greater completeness to the principal thing, or by way of ornament, or for the sake of symmetry.

A part performed by instruments, accompanying another part or parts performed by voices; the subordinate part, or parts, accompanying the voice or a principal instrument; also, the harmony of a figured bass.

something added to complete or embellish or make perfect; "a fine wine is a perfect complement to the dinner"; "wild rice was served as an accompaniment to the main dish"