Guitarrón

a large six-stringed, plucked instrument, usually part of a mariachi ensemble
Guitar

A stringed instrument with a long neck and a flat, hollow body. Its strings are plucked or strummed with the fingers.
Guiro

A Latin American percussion instrument consisting of an open-ended, hollow gourd with parallel notches cut in one side
Gregorian chant
Church music with no rhythm and no harmony. Sung without music by a number of people. Named for Pope Gregory.
Grazioso
Italian for “graceful.”
Grave
Italian for “slow and serious.”
Gong

A flat, circular metal disc which is hit with a mallet.
Gong

A metal disc with a turned down rim that makes a loud, booming sound when struck with a mallet.
Glockenspiel

A percussion instrument with a set of steel bars arranged like the keyboard of a piano. It is played either with two hammers, or with a piano keyboard.
Glissando
A rapid succession of notes, often played on the piano or harp by sliding the fingers quickly over the keys or strings.