protoprotestant en · ADJ
Etymology
From proto- + Protestant.
Meanings
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(not-comparable) Relating to a prototypical form of the Protestant religion.
By no means all these towns proved receptive to the Reformation. Douai, Arras, St. Omer, Mons, Gouda, Utrecht, Amersfoort and Groningen, to list but a few, were only lightly affected, though it would be safe to suppose that most towns, by 1566, contained significant Protestant or protoprotestant minorities.
2012, A. C. Duke, C. A. Tamse, Britain and The Netherlands: Volume VII, page 74: