accompaniment

In music, accompaniment is the art of playing along with a soloist or ensemble, often known as the lead, in a supporting manner as well as the music thus played. An accompaniment figure is a gesture used repeatedly in an accompaniment, such as:Alberti bass and other arpeggiosostinati or riffsHarmonic accompaniment is music played to accompany a melody line; it is usually chordal and played by such instruments as (acoustic or electric) guitar, piano, organ and bass guitar, but it can also be played by instruments that ordinarily play the melody, such as the violin. In most tonal music the melody and accompaniment are written from and share the same group of pitches, while in much atonal music the melody and accompaniment are chosen from entirely separate groups of pitches, often from different hexachords. See also: chord-based.
See more at Wikipedia.org...

(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.
  

(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.
  

Noun
1. an event or situation that happens at the same time as or in connection with another
(synonym) concomitant, co-occurrence
(hypernym) happening, occurrence, natural event
(hyponym) associate
(derivation) attach to, accompany, come with, go with
2. a subordinate musical part; provides background for more important parts
(synonym) musical accompaniment, backup, support
(hypernym) part, voice
(hyponym) descant, discant
(derivation) play along, accompany, follow
3. the act of accompanying someone or something in order to protect them
(synonym) escort
(hypernym) protection
(hyponym) convoy
(derivation) company, companion, accompany, keep company