English Reference
verb · noun

retrofit

v. · n.
US /ˈɹɛtɹoʊˌfɪt/ UK /ɹˌɛtɹəʊfˈɪt/ retro·fit UK spelling retrofits

  1. 01 C1 Advanced Technical

    v.to add new parts or technology to an old building or machine to make it work better.

    v.to supply a device or structure with new components or parts that were not available at the time of original construction.

    Simple

    The city decided to retrofit the old library with solar panels and better windows.

    In context

    Engineers were hired to retrofit the aging bridge with seismic dampers to ensure it could withstand a major earthquake.

    Usage

    Often used in the context of environmental upgrades or safety improvements.

    modernizeupdaterefurbish
  2. 02 C1 Advanced Technical Computing

    v.to add a new feature to an older version of a computer program.

    v.to retroactively supply a fix or feature to a previous version of a software product; synonymous with 'backport'.

    Simple

    The developers had to retrofit the security patch into the older version of the app.

    In context

    While the new interface is exclusive to the current release, the team managed to retrofit the core security updates for legacy users.

    Usage

    Commonly used as a transitive verb where the feature is the object.

    backport
  3. 03 C1 Advanced Technical

    n.a new part or set of changes added to an old machine or building.

    n.an instance of retrofitting or the specific components added during the process.

    Simple

    The energy-saving retrofit cost the company thousands of dollars but saved money later.

    In context

    The building's recent retrofit included a complete overhaul of the HVAC system to meet modern efficiency standards.

Usage retrofit programme

The most disruptive part of the retrofit work was carried out first, and included the insulation of shared walls, flooring and the roof.

BBC News· 21 Aug 2026

From there, the team plans to model potential solutions, principally through updated building codes for new construction and retrofits for existing structures.

Phys.org· 21 Aug 2026

The verb is derived from retro- (prefix meaning ‘back; backward’) + fit (“to equip, supply”). The noun, which is first attested later than the verb, is either derived: * from the verb (see above); or * from retro- + fit (“act of fitting; conformity of elements one to another”).

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Level C1 · Advanced
Frequency Occasional
Updated