'non-allantoidean' originates from English, formed by the prefix 'non-' (from Latin 'non' meaning 'not') combined with 'allantoidean', which derives from New Latin 'allantois' ultimately from Greek 'allantoeis' meaning 'sausage-shaped'.

'allantois' entered scientific New Latin from Greek 'allantoeis' ('sausage-shaped'), later giving rise to the adjective 'allantoidean' in biological terminology; English prefixed 'non-' to produce 'non-allantoidean' to indicate negation.

Initially the Greek term referred to a 'sausage-shaped' form; over time 'allantois' became the technical name for a specific embryonic membrane, and 'non-allantoidean' came to mean 'not pertaining to the allantois'.