'aplasia' originates from New Latin/medical Latin, specifically the word 'aplasia', where the prefix 'a-' meant 'not' and Greek root 'plasis' (from 'plassein') meant 'formation' or 'molding'.

'aplasia' came into English via New Latin/medical usage borrowing directly from Greek 'aplásia' (aplásia), and entered English medical literature in the 19th century as the term for lack of formation.

Initially it meant 'lack of formation' in a general sense in Greek, and it has retained that core meaning in modern medical English as 'failure of development or absence of an organ or tissue'.