solmization
noun
sol·mi·za·tion ˌsäl-mə-ˈzā-shən 
: the act, practice, or system of using syllables to denote the tones of a musical scale
Word History
Etymology
French solmisation, from solmiser to sol-fa, from sol (from Medieval Latin) + mi (from Medieval Latin) + -iser -ize
First Known Use
1730, in the meaning defined above