ar·rant 
/ˈerənt/ adjective
always used before a noun /ˈerənt/ adjective [more arrant; most arrant] somewhat old-fashioned + literary : of the worst kind — used to make a statement more forceful ▪ This is arrant [=utter, complete] nonsense! ▪ an arrant fool
Do not confuse arrant with errant.
