A musical concept which implies taking the long way around, harmonically. It is often used in jazz to extend a phrase or idea.
"Extended dominant" is a fancy way of referring to a dominant of the dominant relative to the key you are in. The dominant (or V7 chord) has a strong tendency to resolve to the tonic (the I chord). Hence if the composer utilizes the dominant of V7 (the 'five of five' or II7) the resolution will extend the dominant function and its musical interest -
II7 --> V7 --> I (in jazz usually Imaj7)
By doing a little math, a composer can extend the dominant function a great deal:
(In C Maj - Roots)
VII7 --> III7 --> VI7 --> II7 --> V7 --> I
(B) (E) (A) (D) (G) (C)
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