Retrofit

Verb

 * 1) To add or substitute new parts or components to some device, structure etc., that were not previously available; to modernize
 * 2) To fix an older version (or older versions) as part of the same process of fixing the newest version

Noun

 * 1) Something that has been retrofitted
 * 2) The act of retrofitting

Adjective

 * of, relating to, or being a retrofit