accompaniment vs concomitant

accompaniment

noun
  • 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, usually performed by instruments, that gives support or adds to the background in music, or adds for ornamentation; also, the harmony of a figured bass. 

concomitant

noun
  • Something happening or existing at the same time. 

  • An invariant homogeneous polynomial in the coefficients of a form, a covariant variable, and a contravariant variable. 

adj
  • Of or relating to the grammatical aspect which expresses that a secondary action is occurring simultaneously to the primary action of the statement. 

  • Accompanying; conjoining; attending; concurrent. 

How often have the words accompaniment and concomitant occurred in a corpus of books? (source: Google Ngram Viewer )