'arminianizer' originates from Modern English, formed from the adjective 'Arminian' plus the verb-forming suffix '-ize' and agentive suffix '-er'; 'Arminian' itself comes from the Latinized name 'Arminius' (Jacobus Arminius), the Dutch theologian after whom the movement is named.

'arminianizer' changed from the personal name 'Arminius' to the adjective/noun 'Arminian' (a follower of Arminius), then to the verb 'arminianize' (to make or become Arminian), and finally to the agent noun 'arminianizer' (one who arminianizes or promotes Arminianism).

Initially the root referred simply to association with 'Arminius' and his teachings; over time derivatives came to mean actively promoting or converting others to those doctrines, which is the current sense of 'arminianizer'.