retrofit

American  

[re-troh-fit, re-troh-fit, re-troh-fit] / ˈrɛ troʊˌfɪt, ˌrɛ troʊˈfɪt, ˈrɛ troʊˌfɪt /

verb (used with object)

retrofitted, retrofit, retrofitting

1. to modify equipment (in airplanes, automobiles, a factory, etc.) that is already in service using parts developed or made available after the time of original manufacture.

2. to install, fit, or adapt (a device or system) for use with something older.

   to retrofit solar heating to a poorly insulated house.

---

verb (used without object)

retrofitted, retrofit, retrofitting

1. (of new or modified parts, equipment, etc.) to fit into or onto existing equipment.

2. to replace existing parts, equipment, etc., with updated parts or systems.

noun

1. something that has been retrofitted.

2. an instance of updating, enlarging, etc., with new or modified equipment.

   A retrofit could save thousands of dollars.

adjective

1. being or characterized by a retrofit.

   retrofit units.

retrofit British  

/ ˈrɛtrəʊˌfɪt /

verb

1. (tr) to equip (a vehicle, piece of equipment, etc) with new parts, safety devices, etc, after manufacture

---

Other Word Forms

• retrofittable
  adjective

Etymology

Origin of retrofit

retro- + fit ¹

Explanation

When you retrofit something, you replace old parts with new ones. You might retrofit an antique car with updated brakes and seat belts, for example. You can use retrofit as a verb, or it can be a noun meaning the new part itself, or something that's added on later. The solar panels on your two hundred year old house are a retrofit, and so is the fancy new stereo in your beat up old car. Retrofit has been around since the mid-1950s, when retroactive and refit were combined into a new word.

Example Sentences

The 'Warmth on Prescription' scheme has been running alongside the NHS Retrofit project funded by NHS Gloucestershire Integrated Care Board, which provided up to £20,000 per property to install measures to improve home energy efficiency.

From BBC • Jan. 13, 2026

Dominion Energy offers the Home Energy Assessment program and the deeper diagnostic Retrofit testing program, according to Michael Hubbard, manager of energy conservation for Dominion Energy in Virginia.

From Washington Post • Apr. 21, 2022

It’s a similar move to the Retrofit Alarm Kit that Ring launched in 2019, which lets you add an existing home alarm system into a new Ring Alarm setup.

From The Verge • Feb. 23, 2022

Retrofit progress has been steady across the city, a Times analysis of city records shows.

From Los Angeles Times • Nov. 22, 2019

He also talks Big Planet’s publishing partnership with Retrofit Comics, a project that finds him serving an editorial role.

From Slate • Oct. 15, 2017