simple past tense and past participle of thread
"The mechanic threaded the bolt through the hole before tightening it with a wrench."
In plain English: To thread something means to pass it through holes or between spaces so that parts fit together tightly.
"He threaded his bike through the crowded market street to avoid traffic."
(of bolts or screws) having screw threads
"The mechanic tightened the threaded bolt to secure the engine cover firmly in place."
Having threads.
"The metal bolts were threaded to allow them to be screwed into the wooden frame securely."
The word threaded is formed by adding the suffix -ed to the noun thread. It describes something that has been fitted with threads or moved along a path like one following a thread.