Orchestra
A large group of performers that include strings, brass, woodwinds and percussion
Organ (MORE)
A multi-keyboard instrument with pedals that control pipes or simulation of pipes which sound by air pressure
Organ Crawl
A tour of the inner parts of a pipe organ
Organistrum
Hurdy-Gurdy
Organology
(Greek) The study of musical instruments
Ornament (MORE)
Musical embellishments
Ostinato
(Italian) A pattern repeated throughout a piece of music or composition
Ottava
(Italian) Octave
Ottoni
(Italian) Brass
Overstringing
In a piano, arranging the strings vertically, overlapping and slanted. (Also called "cross-stringing")
Overture
The musical introduction to a play, musical, opera or oratorio
Two notes played together as a chord that are a perfect fifth apart with no other notes in between
Open String
On a stringed instrument, when a string is played and not fretted
Opera
A musical play, with elaborate costumes and props
Opus
(Latin) A term used with a number as an identifier of a group of musical works
Oral tradition
Music that is passed down from generation to generation without being written down, i.e., folk music
Oratorio
An opera without elaborate costumes and props, usually religious