touch up
1. verb To fix minor flaws in or make minor changes to something. A noun or pronoun can be used between "touch" and "up." I'd just like to touch up my makeup before we leave. All you need to do is touch the wall up with a bit of spackle and paint, and it will be as good as new!
2. noun A minor change or fix. As a noun, the phrase is usually hyphenated. The cover is almost ready, it just needs a few touch-ups before we send it to the printer.
touch something up
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.
touch up
Make minor changes or improvements, as in This wall needs some touching up but not complete repainting. [Early 1700s]
touch up
v. 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.