'full-petaled' originates from the combination of the English adjective 'full' and the noun 'petal'. 'Full' comes from Old English 'full' meaning 'filled', and 'petal' ultimately originates from Greek 'petalon' (via Modern Latin 'petalum' and French), where 'petalon' meant 'leaf'.

'petal' entered English from Modern Latin 'petalum', borrowed from Greek 'petalon' meaning 'leaf', while 'full' is a native Old English word 'full'; the compound form 'full-petaled' developed in modern English by combining these elements and using the adjectival '-ed' on 'petal' to describe flowers.

Initially, the components meant 'full' (completely filled) and 'petal' ('leaf'); over time they combined into the compound describing flowers that are 'having many or fully formed petals', the sense used in modern botanical and horticultural descriptions.