Entry for EPMOW by Philip Tagg
changes: short for chord changes. 1. term used mainly by jazz musicians in the English-speaking world to denote any harmonic progression; 2. such a chord progression forming the basis for improvisation; 3. any progression of at least three chords, often more, recurring consecutively several times during performance of the same number.
Colloquial examples of usage: (i) ‘the La bamba changes go one, four, five’ (see turnaround ); (ii) ‘which changes do you use in the middle eight of Round About Midnight?’; (iii) ‘I was trying to work out the changes on that recording’. See also harmony.