The Collaborative International Dictionary of English v.0.48:

Compatibility \Com*pat`i*bil"i*ty\, n. [Cf. F.
   compatibilit['e].]
   The quality or power of being compatible or congruous;
   congruity; as, a compatibility of tempers; a compatibility of
   properties.
   [1913 Webster]

WordNet (r) 3.0 (2006):

compatibility
    n 1: a feeling of sympathetic understanding
    2: capability of existing or performing in harmonious or
       congenial combination [ant: incompatibility]

The Free On-line Dictionary of Computing (19 January 2023):

compatible
compatibility

    Different systems (e.g., programs, file formats,
   protocols, even programming languages) that can work
   together or exchange data are said to be compatible.

   See also backward compatible, forward compatible.

   (1998-01-15)