The compound adjective "three-note" is a transparent modern English formation, combining the cardinal number "three" with the noun "note." The word "three" descends from the Proto-Indo-European root tréyes, a fundamental numeral that evolved consistently into the Germanic branch, giving Old English þrīe. "Note" entered English via Old French from Latin nota, which originally meant a mark or sign. In the musical context, "note" came to signify a single tone of definite pitch. The compound logically and literally describes anything comprised of or defined by three such musical tones, demonstrating a straightforward descriptive construction in technical and musical vocabulary.

Structure: three (number) + note (sound) - three: From Old English þrīe, þrēo, from Proto-Germanic þrīz, from Proto-Indo-European tréyes. Functions as a numerical root. - note: From Middle English note, from Old French note ("mark, sign, musical note"), from Latin nota ("mark, sign, note, character"). Functions as a nominal root.