'anomoeanism' originates from Greek, specifically the word 'anomoeanismos' (from 'anomoeos'), where the prefix 'a-' meant 'not' and 'omoios' (or 'homoios') meant 'similar'.

'anomoeanism' came into English usage via Late Latin/Church Latin forms such as 'anomoeanus'/'anomoeanismus', themselves derived from the Greek 'anomoeios' (Ἀνόμοιος). Over time the term entered theological English to name the doctrine and its adherents.

Initially it denoted simply 'dissimilarity' (the claim that the Son is unlike the Father); this specific theological sense has been retained as the primary meaning in historical and theological contexts.