From the Greek word pneuma, meaning “breath,” a neume is a note or group of notes sung to a single syllable. This same term came to be used for the graphic notation representing these sounds on the page, which varied greatly across time and geography. Early neumes were textual accents, and another system uses square shapes representing pitch, which still appears in modern notation for Gregorian chant. Neumes commonly appear in plainchant or plainsong.