retrofit

American  

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

verb (used with object)

retrofits, present (3rd person singular) retrofitted, past participle, past retrofit, past participle, past retrofitting present participle

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.

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verb (used without object)

retrofits, present (3rd person singular) retrofitted, past participle, past retrofit, past participle, past retrofitting present participle

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

retrofits plural

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

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Other Word Forms

Derived Forms

• retrofittable
  adjective

Inflected Forms

Nouns

• retrofits
  plural

Participles

• retrofitting
  present
• retrofit
  past
• retrofitted
  past

Conjugated Forms

Present

• retrofit
  simple
• retrofits
  simple
• have retrofit
  perfect
• have retrofitted
  perfect
• has retrofit
  perfect
• has retrofitted
  perfect
• am retrofitting
  progressive
• are retrofitting
  progressive
• is retrofitting
  progressive
• have been retrofitting
  perfect progressive
• has been retrofitting
  perfect progressive

Past

• retrofit
  simple
• retrofitted
  simple
• had retrofit
  perfect
• had retrofitted
  perfect
• was retrofitting
  progressive
• were retrofitting
  progressive
• had been retrofitting
  perfect progressive

Future

• will retrofit
  simple
• will have retrofit
  perfect
• will have retrofitted
  perfect
• will be retrofitting
  progressive
• will have been retrofitting
  perfect progressive

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

Retrofit building permits also have been issued for an additional 2,068 buildings.

From Los Angeles Times • Oct. 20, 2022

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

So we published a few things on our own, and then in 2013, we started co-publishing with Retrofit Comics, which is based out of Philadelphia, so, I think, we’ve released 30 comics since then.

From Slate • Nov. 2, 2017