'round-headed' originates from the combination of 'round' and 'head,' where 'round' meant 'circular' and 'head' referred to the top part of the body or object.

'round-headed' evolved from the Old English word 'rund' meaning 'circular' and 'heafod' meaning 'head,' eventually forming the modern English term 'round-headed.'

Initially, it meant 'having a circular head,' and this meaning has largely remained the same in modern usage.