Arrant & Errant

Arrant is used to emphasize that someone or something is an extreme example of that which is unacceptable: “This is arrant nonsense!”
Errant, on the other hand, means roving or wandering; especially, in search of adventure: “We were reading about an errant traveler.”
It also means straying from the proper course or correct standard: “She could no longer tolerate her errant husband.”