“Tinker” usually means to make small, casual changes to something, especially to repair, improve, or experiment with it. For example: “He likes to tinker with old computers.”

It can also be a noun for a person who traveled from place to place repairing metal household items, though that usage is old-fashioned.

Simple meanings

  • As a verb : to adjust, fix, or mess around with something in a hands-on way.
  • As a noun : an itinerant repair worker, especially one who fixed pans and other metal goods.

Example

  • “She tinkered with the app until it worked better.”

TL;DR

“Tinker” = make small adjustments or repairs, often experimentally.