diatessaron (n.)youdaoicibaDictYouDict
late 14c. as a term in music meaning "interval of a fourth;" 1803 in reference to harmonizings of the gospels, especially that of Tatian (2c.), from Greek dia tessaron, from dia "composed of" (literally "through;" see dia-) + tessaron "four," related to tessares (see four).
harmonize (v.)youdaoicibaDictYouDict
late 15c., "play or sing in harmony," from French harmoniser (15c.), from Old French harmonie (see harmony). Meaning "be in harmony (with), go well together" is from 1620s. Transitive sense "bring into harmony" is from 1700; figurative sense "bring into agreement" is from 1767. Meaning "add harmony to (a melody)" is from 1790. Related: Harmonized; harmonizing.
concertanteyoudaoicibaDictYouDict
"Denoting a piece of music containing one or more solo parts, typically of less prominence than in a concerto", Italian, 'harmonizing', from concertare 'harmonize'.