'atresic' originates from New Latin, ultimately from the noun 'atresia', itself from Greek elements: 'a-' meaning 'not' and a root related to 'trēsis' meaning 'perforation' or 'opening'.

'atresic' developed from New Latin 'atresicus' (adjective relating to 'atresia'), which in turn came from Medieval/Modern Latin 'atresia' and the Ancient Greek components; the medical English adjective 'atresic' was formed by adding the English adjectival suffix -ic to the classical/Neo-Latin base.

Initially the Greek-based formation referred literally to 'absence of an opening' (lack of perforation); in modern medical English it is used adjectivally to describe structures that are congenitally or pathologically closed or undeveloped (relating to atresia).