'athanasianism' originates from Greek via Latin and New Latin, specifically the name 'Athanasius', where the prefix 'a-' meant 'not' and 'thanatos' meant 'death' (thus conveying 'immortal').

'athanasianism' developed from the personal name 'Athanasius' (Greek Ἀθανάσιος) combined with the English suffix '-ism' (from Latin/Greek usage) to denote a system of beliefs; the term entered English theological vocabulary via Medieval and New Latin usage and became the modern English 'athanasianism'.

Initially it referred specifically to doctrines or followers directly associated with Athanasius himself; over time it came to denote more broadly the doctrinal positions expressed in the Athanasian Creed and related Trinitarian theology.