'bell-shaped' originates from Modern English compounding of the words 'bell' and 'shape', where 'bell' referred to the ringing hollow metal object and 'shape' meant 'form' or 'appearance'.

'bell' comes from Old English 'belle' (from Proto-Germanic *bellōn, likely imitative of the sound), and 'shape' comes from Old English 'sceap'/'scieppan' (from Proto-Germanic *skapiz, meaning 'form' or 'creation'); the compound 'bell-shaped' developed in later Modern English by combining the noun 'bell' with the past-participial adjective-forming use of 'shape' + '-ed'.

Initially, 'bell' denoted the physical object that rings and 'shape' denoted form; combined as 'bell-shaped' it originally and principally meant 'having the form of a bell', and this literal sense has remained while the phrase has also been extended metaphorically (e.g., 'bell-shaped curve').