'Arianist' originates from New Latin, specifically the word 'Arianista,' where '-ist' indicated 'one who follows' and 'Arian' referred to the followers of Arius.

'Arianist' changed from Late Latin 'Arianista,' which derived from Latin 'Arianus' (meaning 'of or relating to Arius') and ultimately from the proper name 'Arius' (a 4th-century Alexandrian presbyter). The term entered English usage to denote followers of Arianism.

Initially, it meant 'a follower of Arius' (a specific historical individual and his teachings), and over time it retained that meaning while also being used more broadly for adherents of Arian theological positions.