, the term command
has the following meanings:
1. An order for an action to take place.
2. In data transmission, an instruction sent by the primary station instructing a secondary station to perform some specific function.
3. In signaling systems, a control signal.
4. In computer programming, that part of a computer instruction word that specifies the operation to be performed. See command (computing) for detail.
5. Loosely, a mathematical or logic operator.
Source: from Federal Standard 1037C and from MIL-STD-188