retrofitting

/R EH1 T R OW0 F IH0 T IH0 NG/
verb
  1. 1

    To add or substitute new parts or components to some device, structure etc., that were not previously available; to modernize

  2. 2

    To fix an older version (or older versions) as part of the same process of fixing the newest version; to backport

    โ€œThe bug was so bad that we had to retrofit our patch to the last three releases, as well as the newest release.โ€

noun
  1. 1

    The process by which something is retrofitted.

Source: https://en.wiktionary.org/wiki/retrofit, https://en.wiktionary.org/wiki/retrofitting