The phrase "worn to threads" implies that something has been excessively used and is now in a state of disrepair. There are several synonyms to describe this state: frayed, tattered, worn out, threadbare, dilapidated, ragged, shabby, and battered. Each of these words describes an item that has been used for too long and is now either falling apart or is no longer fit for use. These synonyms can be used interchangeably to imply the wear and tear that an item has undergone. Whether it's a pair of jeans or an old chair in a room, these words can help to precisely describe the state of an item that's past its prime.