solmization

/ˌsɒlmɪˈzeɪʃən/
noun
1.
(music) a system of naming the notes of a scale by syllables instead of letters derived from the 11th-century hexachord system of Guido d'Arezzo, which assigns the names ut (or do), re, mi, fa, sol, la, si (or ti) to the degrees of the major scale of C (fixed system) or (excluding the syllables ut and si) to the major scale in any key (movable system) See also tonic sol-fa
Word Origin
C18: from French solmisation, from solmiser to use the sol-fa syllables, from sol1 + mi