Idiomatic To make slight corrections or adjustments to; to fill in or perfect.
Use a small brush to touch up the paint anywhere it is uneven.
The undoubted facts that survived a comparison were few and meagre, for in each case a conscientious journalist had touched up a few vague or doubtful details according to his own ideas of probability.1914, Ernest Bramah, Max Carrados:
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UK, Idiomatic To fondle or to grope someone, usually in an inappropriate way.
The creep was trying to touch up my girlfriend.
I think you remember him! He made me go into the back of his shop and he touched me up, do you remember? And afterwards we shared out the money from the Cinzano. In the end he got round to doing something disgusting, that guy, something disgusting, quite disgusting.2019, Copi, “Eva Perón”, in Four Plays, Alma Books, →ISBN: