early 12c., from Old French acorder (12c.) "reconcile, agree, be in harmony," from Vulgar Latin *accordare "make agree," literally "be of one heart, bring heart to heart," from Latin ad- "to" + cor (genitive cordis) "heart" (see heart). Related: Accorded; according.
late 13c., accourd, from Old French acord "agreement," a back-formation from acorder (see accord (v.)).
Also,of one's own free will. Voluntarily, without prompting or coercion, as in The entire audience rose of their own accord, or No, I'm climbing this mountain of my own free will. The first term dates from about 1450, the variant from about 1600.