doo
n. countablen. a nonsense sound used in music when a singer wants to follow a melody without using real words. It is very common in jazz and pop songs.
n. a vocable or nonsense syllable used in vocal music to carry a melodic line without semantic content. Frequently associated with scat singing or doo-wop backing vocals.
The singer finished the song with a soft 'doo-doo-doo'.
The backing vocalists provided a rhythmic foundation by repeating a simple 'doo' pattern behind the lead singer.
In jazz improvisation, a vocalist might substitute complex lyrics for a series of 'doo' and 'dah' syllables to focus the listener's attention entirely on the melodic and rhythmic phrasing.
1950s, from child speak.
Clipping of Skidoo.
Often used in onomatopoeic strings to represent a bass line or a simple melody.