What is the meaning of retrofit?

noun

• A component or accessory added to something after it has been manufactured.
• The act of adding a component or accessory to something that did not have it when it was manufactured.
  • usage: "the court ordered a retrofit on all automobiles"

verb

• Provide with parts, devices, or equipment not available or in use at the time of the original manufacture.
  • usage: "They car companies retrofitted all the old models with new carburetors"
• Fit in or on an existing structure, such as an older house.
  • usage: "The mansion was retrofitted with modern plumbing"
• Substitute new or modernized parts or equipment for older ones.
  • usage: "The laboratory retrofitted to meet the safety codes"