Accompanier :: Accompanier (n.) He who, or that which, accompanies..
Accompaniment :: Accompaniment (n.) 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..
Accompaniment :: Accompaniment (n.) 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..
Accompanist :: Accompanist (n.) The performer in music who takes the accompanying part.