'non-allantoic' originates from the Latin prefix 'non' (meaning 'not') combined with 'allantoic', which ultimately comes from the Greek 'allantois' (originally meaning 'sausage-shaped' or 'sausage'), where 'non-' meant 'not' and 'allantois' referred to the sausage-shaped embryonic membrane.

'allantois' entered English via Modern Latin/Neo-Latin from Greek 'allantois' (or related Greek forms meaning 'sausage-like'); the adjective 'allantoic' developed from that noun, and later the negative prefix 'non-' was attached in English to form 'non-allantoic'.

Initially related to the Greek sense describing shape ('sausage-shaped') and then used anatomically for the embryonic structure 'allantois'; over time 'allantoic' came to mean 'relating to the allantois', and 'non-allantoic' now means 'not relating to the allantois'.