Origins
The word 'skin' is a Viking-era borrowing from Old Norse that illustrates one of the most common patterns of Norse influence on English: a Scandinavian word entering the language and displacing or restricting the meaning of a native synonym. Before the Norse settlement of England, Anglo-Saxons used 'hȳd' (hide) as their primary word for both animal skin and the outer covering of the human body. The arrival of Old Norse 'skinn' created a doublet that eventually resolved through semantic specialization.
Old Norse 'skinn' referred primarily to prepared animal hides — skins that had been removed from the animal, typically for use as leather or parchment. The word descended from Proto-Germanic *skinþą, which is likely connected to the PIE root *sek- meaning 'to cut,' reflecting the concept of skin as something cut or peeled away from the body. This same root produced Latin 'secare' (to cut), the source of English 'section,' 'sector,' and 'dissect.'
The word entered English through the dense contact between Norse-speaking settlers in the Danelaw and the English-speaking population. It appears in English texts from around 1200 onward, initially in the Norse sense of 'animal hide' but quickly expanding to cover human skin as well. By the fourteenth century, 'skin' had become the standard English word for the outer covering of any living body, while 'hide' was increasingly restricted to the skins of dead animals, particularly those prepared for commercial use.
Development
This semantic division — 'skin' for the living, 'hide' for the dead — is an English innovation not found in the Scandinavian languages themselves. Swedish and Norwegian 'skinn' still covers both meanings, as does Danish 'skind.' Only in English did the coexistence of the Norse loan and the native word force a specialization that neither language had independently developed.
The initial /sk-/ cluster is one of the most reliable indicators of Norse origin in English vocabulary. In Old English, the original Proto-Germanic /sk-/ had already undergone palatalization to /ʃ/ (spelled 'sc-' and later 'sh-'). Words that retain /sk-/ in English were therefore borrowed after this sound change had occurred, and the overwhelming majority came from Old Norse. This creates revealing pairs: 'shirt' (native English, from Old English 'scyrte') versus 'skirt' (Norse, from 'skyrta') — both from the same Proto-Germanic word but entered English through different paths. Similarly, 'shin' is native English (Old English 'scinu'), while 'skin' is Norse.
The word has proven remarkably productive in English, generating dozens of compounds and derivatives. 'Skinny' appeared in the late sixteenth century. 'Skinflint' (a miser) dates from the early eighteenth century, from the idea of someone so stingy they would skin (pare down) a flint stone to save money. 'Skin-deep,' meaning superficial, was first used by the poet John Davies in 1616. The compound 'sheepskin' became slang for a diploma because university degrees were traditionally written on parchment made from sheep hide.
Figurative Development
In the twentieth century, 'skin' took on technological metaphors: the outer covering of an aircraft fuselage is its 'skin,' software interfaces have 'skins,' and buildings have 'skin systems.' Each of these metaphorical extensions preserves the original Norse concept of an outer covering that can be removed or changed — the idea of skin as something separable from the body beneath it, rooted in the word's origins as a term for prepared animal hides.