1. To cause something to be more rough or coarse to the touch. (In each usage, a noun or pronoun can be used between "roughen" and "up.") Make sure to roughen the concrete up before it dries, otherwise it will become very slippery when wet. I would suggest roughening up the soles of your dress shoes to give them a better grip while you walk.
2. To cause someone to be more violent, disorderly, or coarse in manner or behavior. My time in prison only served to roughen me up even more than I had been before. These streets will roughen up even the most tender of young men. I suspect that time in the military will roughen her up.
3. To use physical violence against someone, especially as a means of harassment or bullying. (A less common variant of "rough up.") The mob boss sent around a couple of goons to roughen up Thomas for not paying them protection money. I managed to get video footage of the police roughening the man up on the street before arresting him.
See also: up
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.