touch somebody/something ↔ up phrasal verb ( see also ↑ touch )
1 . to improve something by changing it slightly or adding a little more to it:
She quickly touched up her lipstick.
The photograph had obviously been touched up.
The speech he finally gave had been touched up by his staff.
2 . British English informal to touch someone in a sexual way when they do not want you to:
He was accused of touching up one of his students.