1690s, "to contrive, adjust;" 1707, "to contrive and arrange mutually," from French concerter and directly from Italian concertare "to bring into agreement," apparently from Latin concertare "to contend with zealously, contest, dispute, debate" from assimilated form of com "with" (see con-) + certare "to contend, strive," frequentative of certus, variant past participle of cernere "separate, distinguish, decide" (from PIE root *krei- "to sieve," thus "discriminate, distinguish"). Related: Concerted; concerting.
<a href="https://www.etymonline.com/word/Concerted">Etymology of Concerted by etymonline</a>
Harper, D. (n.d.). Etymology of Concerted. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/Concerted