G
G Clef: A clef that indicates which line represents G on a staff. 
See C clef, F clef.
Gallant: (Style Gallant)an 18th century compositional style that was light, elegant, non- contrapuntal, and highly ornaments.
German Sixth Chord: An augmented
sixth chord, which contains a flat third from the tonic.
Gloria: "Glory". In the Mass,
the second part of the ordinary.
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.
Grace Note: A note, or notes that are played quickly, usually before
the beat. See ornament.
Gradual: 1) The response sung in a mass between the Epistle and the
Gospel. 2) The book that acts as the choir or congregation's musical companion
to the Missal.
Grand Opera: An opera on a large scale, usually entirely sung, in contrast to comic
opera.
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).
Grupetto: Also known as the Turn. An ornament used in vocal and instrumental music consisting of four notes that move up and down 'around' a given pitch, using that pitch as a tonal center, before resolution to the final note which is comonly a third above the 'given pitch.'
example:
Guitar: A string instrument from Spain, with a large, flat-backed sound box, violin-like curved shape, a fretted neck, and six strings.
