A delay effect where the delay time can be subdivided into multiple “taps” allowing for the creation of rhythmic delay effects. For example, you might set the delay for 480 milliseconds, then have taps at 1/2 that time (240ms) and 1/3 that time (160ms). (Contrast this with a “normal” delay, where you would only be able to get repeats at even intervals, in this example, 120, 240, 360, and 480ms or 160, 320, and 480ms, but not a combination of the two.)
This creates the effect of a rhythm based on repeats at 160, 240, and 480 milliseconds. With the addition of feedback for multiple repeats, the rhythmic effect becomes even stronger.
At shorter delay times, multi-tap delays can also be used to create textural sonic effects, as the delay taps begin to wash into one another.