ret·ro·fit 
(rĕtrō-fĭt′)
(rĕtrō-fĭt′)tr.v. ret·ro·fit·ted or ret·ro·fit, ret·ro·fit·ting, ret·ro·fits
1. To outfit (a device, vehicle, building, or system) with newly developed or previously unavailable parts or equipment: retrofit cars with new safety features.
2. To install or fit (a device or system, for example) for use in or on an existing structure, especially an older dwelling.
n.
1. An instance of retrofitting: a retrofit for the heating system.
2. Something that has been retrofitted.
retro·fit′ adj.
ret′ro·fitta·ble adj.
retro·fit′ter n.