The Collaborative International Dictionary
Progressionist \Pro*gres"sion*ist\, n.
One who holds to a belief in the progression of society toward perfection.
One who maintains the doctrine of progression in organic forms; -- opposed to uniformitarian.
--H. Spencer.
Wiktionary
n. 1 An advocate of social progress, ideally towards perfection 2 (context biology English) A person who holds that all life forms gradually evolve to a higher form
Usage examples of "progressionist".
Yet because he had made himself a leader of the Progressionist Party, it was unwise to dismiss him publicly.
The recent victories all along the line of women over men in examination-rooms, and their more or less successful ventures in the fields of law, medicine, and newspaper enterprise, would be more appalling to man and encouraging to the progressionists, but for the obstinate though obvious adhesion of the great mass of woman-kind to the trick bequeathed to them by their great-great-grandmothers of trying to look as well as they can.