Roughen is a verb that means to make something rough or uneven. It can be used to describe the surface of an object, such as sandpaper, or the texture of a material, such as fabric. The crossword solution for the term roughen is CHAP, which is an abbreviation for the word chaparral, a type of shrubland found in dry regions. Chaparral is characterized by its rough and uneven terrain, making it a fitting clue for the term roughen.