To refit means to repair, renovate, or update something (especially a ship, aircraft, or building) by installing new parts or equipment. When a naval vessel goes into port for a refit, workers might replace outdated radar systems, repair the engines, upgrade the crew quarters, or repaint the hull. The ship emerges ready for many more years of service.

Wooden sailing ships required constant maintenance: replacing worn sails, fixing leaky hulls, and updating rigging. A major refit might take months in a shipyard.

Today, we refit all sorts of things. A school might refit its computer lab with new machines and faster internet. A factory might refit its assembly line with modern robots. An old building might be refitted as apartments, with workers adding new plumbing, electrical systems, and insulation while keeping the original brick walls.

Refitting is different from simple repairs or total replacement. It means taking something that still has value and carefully upgrading it to meet current needs. When you refit something, you're saying it's worth saving and improving rather than throwing it away.