In signal processing, the term pulse has the following meanings:

1. A rapid, transient change in the amplitude of a signal from a baseline value to a higher or lower value, followed by a rapid return to the baseline value.
2. A rapid change in some characteristic of a signal, e.g., phase or frequency, from a baseline value to a higher or lower value, followed by a rapid return to the baseline value.
3. In telephony pulse dialing is a way of dialing a telephone number using interrupted electrical pulses (see rotary dial).

Original source: from Federal Standard 1037C and from MIL-STD-188

See also: Pulse forming network