1665, from Fr., from It.
concerto "concert, harmony," from
concertare "bring into agreement," in L. "to contend, contest," from
com- "with" +
certare "to contend, strive," freq. of
certus, var. pp. of
cernere "separate, decide" (see
crisis). Before the word entered Eng., meaning shifted from "to strive against" to "to strive alongside." But Klein considers this too much of a stretch and suggests L.
concentare "to sing together" (from
con- +
cantare "to sing") as the source of the It. word. Sense of "public musical performance" is 1689.
Concerto was borrowed 1730 directly from It. as a musical term.