Definition from Wiktionary, the free dictionary
- The state of being compatible; in which two or more things are able to exist or perform together in combination without problems or conflict.
- (telecommunications) the capability of two or more items or components of equipment or material to exist or function in the same system or environment without mutual interference.
- (computing) the ability to execute a given program on different types of computers without modification of the program or the computers. See backward compatibility and forward compatibility.
- (computing) 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.
- (structural analysis) the continuity or good fit of material or members or components while being deformed.
Related terms 
the capability to exist without mutual interference