'skull-less' originates from the English word 'skull' combined with the suffix '-less', where 'skull' refers to the bony structure of the head and '-less' indicates absence.

'skull' changed from the Old Norse word 'skalli' meaning 'bald' or 'bare', and eventually became the modern English word 'skull'.

Initially, 'skull' referred to the bony structure of the head, and 'skull-less' evolved to mean lacking this structure.