1. Surface roughness or simply roughness is the quality of a surface of not being smooth and it is hence linked to human (haptic) perception of the surface texture. From a mathematical perspective it is related to the spatial variability structure of surfaces, and inherently it is a multiscale property. It has different interpretations and definitions depending on the disciplines considered. (Wikipedia). 2. Surface roughness is defined as the non-uniformity of small peaks and troughs on a surface, affecting the adhesion of fouling. It can be enhanced to improve the bonding between a coating and a metal substrate, but its influence on antifouling coating performance is limited. (Science direct, AI generated definition based on: Desalination Volume 553, 1 May 2023, 116504)