solfège

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Solfeggio.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun 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 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.