When speaking of clothing or fabric, "worn to a thread" typically means that an item has been used extensively and is now in a state of disrepair. Some possible synonyms for this phrase might include "threadbare," "ragged," "frayed," "tattered," or "worn-out." These terms all convey a similar sense of wear and tear, suggesting that the item in question is no longer in its original state of quality or good condition. Whether it's a well-loved sweater or a favorite pair of jeans, we all have clothes that we wear until they are virtually falling apart at the seams!