noun
1.
something added to a principal thing usually to increase its impact or effectiveness
her song had a soft orchestral accompaniment
Synonyms: augmentation, complement, enhancement, enrichment
Related Word: accessory, addition, supplement; aid, assistance, help
2.
an accompanying individual, situation, or occurrence
smog is an inevitable accompaniment of excessive numbers of automobiles
Synonyms: associate, companion, concomitant, consort, fellow, mate
Related Word: attendant, colleague, comrade, partner; corollary, equivalent