This was the contemporary term for adherents of John Calvin in Geneva while he was living. It pre-dates the nasty disputes that erupted after 1609 with the disputes of the Remonstrants.
Sometimes I think it is a more comprehensive term than Calvinist which came into usage much later, a term of derision invented by the Jesuits.
So, we can all be Calvinians and approach the Arminian dispute freshly, like brothers in the fellowship of Geneva.
Calvinian.
What a great and accurate term.
Somehow, the word "Calvinist" elicits all sorts of slanderous charges of "worshipping Calvin."
But the term "Arminian" is supposedly just fine.
Calvinian.