'dialypetalous' originates from New Latin, specifically the word 'dialypetalis', where the prefix 'dialy-' (from Greek διά, dia-) meant 'apart' or 'separate' and 'petal-' (from Greek πετάλον, petalon) meant 'leaf' or 'petal'.

'dialypetalis' was formed from Greek elements 'dia-' + 'petalon' and entered scientific New Latin usage before being adopted into modern English as 'dialypetalous'.

Initially it meant 'having separate petals' in botanical descriptions, and this basic meaning has been retained in modern usage.