Where does “contrariantly” come from?

contrariantly (English) comes from English contrariant, from Latin contrarians, from Latin contrariare — to oppose.

contrariantly (English): In a contrary fashion

Definitions

Step	Language	Word	Meaning
1	English	contrariant	contrary; opposed; antagonistic; contradictory; A...
2	Latin	contrarians	—
3	Latin	contrariare	to oppose

contrariantly — Etymology, Origin & Word History | Etymology Explorer