'nut-shaped' originates from Modern English, specifically a compound of 'nut' + past-participial adjective 'shaped', where 'nut' meant 'a nut (seed or fastener)' and 'shaped' meant 'having the form of'.

'nut' originates from Old English 'hnutu' (meaning 'nut, seed'), and 'shape' comes from Old English 'sceáp'/'scieppan' (meaning 'form, create'); the compound 'nut-shaped' developed by combining the noun and the past participle to form a descriptive adjective in later English.

Initially it literally described something 'given the form of a nut', and over time it has been used both for resemblance to the edible seed and to the mechanical fastener; the core idea of 'having the form of a nut' has remained.