roughen

the word 'roughen' is a transparent english formation from the late 16th century, combining the native adjective 'rough' with the productive verb-forming suffix '-en'. the adjective 'rough' itself descends from old english rūh, meaning shaggy or hairy, a term which can be traced back to proto-germanic rūhwaz and ultimately to the proto-indo-european root kreu-, meaning 'to be crusty, rough'. the suffix '-en' is a native english morpheme used to derive verbs from adjectives, indicating a change of state. thus, the literal construction 'to make or become rough' has remained perfectly aligned with its modern abstract meaning, showcasing a clear and logical morphological process within the english language.

Structure: rough (adjective) + en (verb suffix) rough (from old english rūh, meaning hairy, shaggy, coarse; functions as the descriptive base). en (from old english -nian, a verb-forming suffix; functions to indicate 'to become or make').