'double-flowered' originates from English, combining 'double' (from Old French 'double', ultimately from Latin 'duplus' meaning 'twofold') and 'flowered' derived from 'flower' (Old French 'flor', from Latin 'flos, floris' meaning 'flower') with the adjectival suffix '-ed'.

'double-flowered' formed in post-Medieval English by compounding 'double' + past-participial adjective 'flowered' (literally 'having flowers'), reflecting descriptive botanical usage; the element 'double' itself came into English via Old French from Latin 'duplus'.

Initially the compound literally suggested 'having twofold or twice the flower' (a more literal 'double' sense); over time it became a specific botanical term meaning 'having extra or multiple layers of petals (i.e. double blooms)'.