a method of sight singing music that uses the syllables do (originally ut), re, mi, fa, sol (or so), la, and si (or ti) to represent the pitches of the scale, most commonly the major scale. The fixed-do system uses do for C, and the movable-do system uses do for whatever key the melody uses (thus B is do if the piece is in the key of B)
the system in which the notes of the musical scale are represented by seven short words, do, re, mi, fa, so, la, ti, which are used especially in singing (sol + fa)