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.

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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

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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

Riot Platforms will make around $90 million in capital expenditures to retrofit the Rockdale facility.

From Barron's • Jan. 16, 2026

A report from the community development research nonprofit Headwaters Economics found a complete home retrofit using affordable materials costs between $23,000 and $40,000.

From Los Angeles Times • Nov. 24, 2025

Airbus had been line-fitting the change since late 2022 with plans to make it available for retrofit on existing aircraft delayed by steel shortages after Russia’s invasion of Ukraine.

From The Wall Street Journal • Nov. 18, 2025

The EAC suggested offering people better incentives to build and live in "carbon-friendly homes", or to retrofit existing ones.

From BBC • Nov. 16, 2025

The Center has since benefitted by a forty-million-dollar retrofit, but there's still enough forest and swamp on the facility for the Border Patrol to put in tracking practice.

From The Hacker Crackdown, law and disorder on the electronic frontier by Sterling, Bruce