A compositional tool which begins as a chord tone, becomes a non-chord tone as the harmony surrounding it is altered and then eventually returns to its original function as a chord tone.

The harmony surrounding a pedal point often times ends up acting as an embellishment to the pedal point because the pedal is so strong, harmonically. It is often times found in the bass, and is often the I (tonic) chord found at the end of a cadence. Here, let me illustrate:

4    d        |    b b  b    |   ||
4          d  |            b |   ||  
                    (IV) (vii)
  V              I-------------I  
The 4/4 bit with the b's and d's are a representation of notes and what not, but it isn't literal at all. The V, I, etc under the line is what a harmonic analysis of a pedal point would look like. The V resolves to the I and then harmonic ornamentation causes the melodic focal point to change around I (the pedal point) while the harmonic focus, though bent a little, remains constant.