bone-thin

The compound adjective "bone-thin" is a modern English formation that follows a long-standing Germanic pattern of creating intensive or descriptive compounds by combining two native words. The first element, "bone," serves as a metaphorical standard of extreme leanness, evoking the image of a body so lacking in flesh that the underlying skeletal structure is apparent. The second element, "thin," descends from the Proto-Germanic thunnuz, itself from the Proto-Indo-European root ten- meaning "to stretch," which also gives rise to words like "tender" and "tenuous," carrying a sense of being drawn out and thus narrow or slight. The logic of the compound is vividly literal, directly linking the visibility of bones to the ultimate degree of thinness, creating a stark and evocative descriptor for emaciation.

Structure: bone (body part) + thin (not thick) - bone: From Old English bān, meaning a piece of the hard tissue forming the skeleton. In this compound, it functions as a noun used attributively to intensify the following adjective. - thin: From Old English þynne, meaning having little depth or having little flesh. In this compound, it functions as the core adjective describing a physical state.