'allantoinic' originates from 'allantoin', which is derived from the Latin word 'allantois', referring to a fetal membrane in mammals, where 'allanto-' meant 'sausage' due to its shape.

'allantois' transformed into the French word 'allantoïne', and eventually became the modern English word 'allantoin' through scientific nomenclature.

Initially, it referred to a fetal membrane, but over time it evolved into its current meaning related to a compound used in skin care.