Roughness refers to the unevenness or irregularity in a surface, often characterized by bumps, ridges, or other textural features. It can be measured and quantified using various metrics such as average roughness height (Ra), root mean square roughness (Rq) or maximum roughness depth (Rt). In general usage, the term "roughness" may also refer to harshness, coarseness, or lack of refinement in behavior, manners, or appearance.