A circuit that, when fed a pulse wave or square wave, outputs a square wave whose frequency is an exact integer division of the input. This creates "subharmonics" in the same way that multiplying the frequency by an integer ratio creates a harmonic; for example, a division by 2 results in one octave lower, and a division by 3 results in an octave plus a fifth lower. When mixed with the input, it adds more bass or "body" to the signal. Many synths feature, as part of their VCO circuits, a suboscillator which consists of a divide-by-2 pulse divider.
Pulse dividers are usually implemented using digital counter circuits. The counter is pre-loaded with the desired divisor, and it counts down one step each time it sees the leading edge of the input signal. When it counts to zero, it reverses the state of the output (from high level to low level or vice versa), and then the count is reloaded. This explains why the basic pulse divider always outputs square waves.