What this suffix does
-skinned forms compound adjectives that describe both the literal quality of skin and the figurative capacity to absorb criticism, insult, and difficulty without damage. Thick-skinned and thin-skinned are among the most psychologically precise compounds in English: they describe not just how someone responds to criticism but how they are constituted to respond to it. Dark-skinned, fair-skinned, and brown-skinned describe physical appearance. The figurative compounds (thick-skinned, thin-skinned) are the more literarily interesting: they use skin as the boundary between self and world, suggesting that resilience is a kind of membrane thickness.