1. A piece of material that is used to mend fabric, or an item of clothing, with a piece of material over a hole or a weak spot in it: Mary's grandmother patched up the elbows of her husband's favorite jacket because the woolen cloth had worn through.
2. Something that is put over a wound or an injury to help the healing process: Monroe's doctor told him that he should patch his mouth shut whenever he felt the need to smoke in order to help him stop smoking.