CompatibilityIn telecommunication, the term compatibility has the following meanings:
2. In computing, the ability to execute a given program on different types of computers without modification of the program or the computers.
3. The capability that allows the substitution of one subsystem (storage facility), or of one functional unit (e.g. , hardware, software), for the originally designated system or functional unit in a relatively transparent manner, without loss of information and without the introduction of errors.
Source: from Federal Standard 1037C and from MIL-STD-188 and from the Department of Defense Dictionary of Military and Associated Terms