godan verb (-su), transitive verb
wear out; use up; use until worn
Transitive verb meaning to use something so much that it becomes old, worn, or no longer usable. Often implies long or heavy use.
この靴はもう使い古したから、新しいのを買わないと。
I've worn out these shoes, so I need to buy new ones.
He's been using the same phrase so much it's become worn out.