Definition of touch up. transitive verb. 1 : to improve or perfect by small additional strokes or alterations : fix the minor and usually visible defects or damages of. 2 : to stimulate by or as if by a flick of a whip. Define touch up (phrasal verb) and get synonyms. What is touch up (phrasal verb)? touch up (phrasal verb) meaning, pronunciation and more by Macmillan . Synonyms for touch up on at Thesaurus.com with free online thesaurus, antonyms, and definitions. Find descriptive alternatives for touch up on. 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. See also: touch, up. Touch-up definition, an act or instance of touching up: Her makeup needed a touch-up. See more. touch up, to make minor changes or improvements in the appearance of. to modify or improve (a painting, photograph, etc.) by adding small strokes or making slight changes. to rouse by or as if by striking: This should touch up your memory. touch up something definition: to improve something with small changes: . Learn more. Touch up definition: to put extra or finishing touches to Meaning, pronunciation, translations and examples. Noun. touch-up (plural touch-ups). A slight correction or adjustment. The frosting just needs a little touch-ups to be smooth and even.