A system of solmization using the solfa syllables: do, re, mi, fa, sol, la, ti WordNet 3.0 & Open English WordNet

Tonic sol-fa is a pedagogical technique for teaching sight-singing, invented by Sarah Ann Glover of Norwich, England and popularised by John Curwen, who adapted it from a number of earlier musical systems. Wikipedia

A method of teaching sight-singing Wikipedia Disambiguation

Music teaching method Wikidata

A method of sight singing that uses the syllables do (originally ut), re, mi, fa, sol (or so), la, and si (or ti) to represent the seven principal pitches of the scale, most commonly the major scale. The fixed-do system uses do for C, and the moveable-do system uses do for whatever key the melody uses (thus B is do if the piece is in the key of B). The relative natural minor of a scale may be represented by beginning at la. Wiktionary

Method of sight singing. Wiktionary (translation)