Accompaniment
Part of speech: noun
Definition: That which gives support or adds to the background in music, or adds for ornamentation. 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.
Attendant
Part of speech: noun
Definition: One who attends; one who works with or watches something.
Part of speech: adjective
Definition: Going with; associated; concomitant.