Onion skin refers to the thin, nearly transparent layer of the onion that is between the outer paper-like skin and the edible flesh of the onion. Although 'onion skin' is commonly used to describe this specific layer, there are several other synonyms that can be used to describe it. Some of the synonyms for onion skin include 'papery skin', 'membrane' or 'sheath,' and 'outer layer.' Other synonyms that describe the appearance or texture of onion skin include 'delicate,' 'fragile,' and 'translucent.' The use of different synonyms for onion skin depends on the context and the specific language used.