/ ˈretrəʊfɪt; NAmE -troʊ-/ verb
( -tt- ) [ vn ] to put a new piece of equipment into a machine that did not have it when it was built; to provide a machine with a new part, etc. :
Voice recorders were retrofitted into planes already in service.
They retrofitted the plane with improved seating.
► retro·fit noun
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WORD ORIGIN
1950s: blend of retroactive and refit .