ETYMOLOGY
from Latin operatorius (creating, forming) + -ous
EXAMPLE
“…For no Lesse are they effectuall to transubstantiate the cup, then their wordes spoken of the bread are operatorius & myghty to transubstātiate the bread. For as they say of the bread, Thys is my body, so say they of the Cup, This cup is the new testament…”
From: Two Notable Sermons
By John Bradford, 1574
Lexicophilia 