the compound adjective 'thick-skinned' is a native english formation, combining germanic roots to create a metaphorical meaning. the old english word 'þicce' (thick) and the old norse loan 'skinn' (skin) were joined, with the adjectival suffix '-ed' added to the noun 'skin'. literally, it describes a physical trait of having a dense outer layer, as seen in animals like elephants or rhinoceroses. by the 16th century, this literal descriptor was applied figuratively to people, implying they possessed a metaphorical protective layer that made them impervious to verbal attacks or slights, much like thick physical skin protects against physical injury. this evolution from a concrete physical description to an abstract psychological one is a classic example of semantic extension based on analogy.

Structure: thick (dense) + skin (outer covering) + ned (adjective suffix) thick (from old english 'þicce', meaning dense or not thin; an adjective). skin (from old norse 'skinn', meaning animal hide or outer covering; a noun). ned (a variant of the past participle suffix '-ed', used to form adjectives from nouns, indicating 'having the quality of').