to fix up the minor flaws in something; to repair a paint job on something. It's only a little scratch in the finish. We can touch it up easily.Tom touched up the scrape with a little paint.
to improve something by making small changes We didn't redo the kitchen, just really touched it up by painting the cabinets.Chris went to the ladies' room to touch up her makeup.
To improve something by making minor corrections, changes, or additions: I touched up the nicks in the paint to prevent the metal from rusting. The author touched an old essay up and submitted it for publication.