G: The key of G.
Glissando: Gliss. The rapid scale achieved by sliding the nail of the thumb or third finger over the white keys of the piano. Glissando is commonly used in playing the harp. For bowed instruments glissando indicates a flowing, unaccented playing of a passage.
Golden Section: A mathematical proportion where the ratio between a small section and a larger section is equal to the ratio between the larger section and both sections put together. Used by many 20th century composers, especially Bela Bartok, to determine the point of climax for a given work.
Gong: An east and southeast asian percussion instrument that takes the form of a flat, circular metal disc which is struck with a mallet, producing a loud sound with a fundamental note and rich overtones.
Grace Note: A note, or notes that are played quickly, usually before the beat. See ornaments.
Grand Piano: A piano where the frame and strings are horizontal, with the strings extending away from the keyboard, in multiple sizes from baby grand - about 5 feet long - to concert grand - about 9 feet long.
Grand Staff: The combination of a staff line notated in treble clef with one notated in bass clef. Used primarily in scoring for piano, and other keyboard instruments, this staff is also sometimes used to score vocal works, such as hymns.
Gregorian Chant: A body of chants of the Roman Catholic Church, most of which are part of two liturgical rites, the Mass and the Offices. Origins traditionally are ascribed to the period of Pope Gregory I (590-604).
Guitar: A plucked string instrument from Spain, with a large, flat-backed sound box and violin-like curved body.