1911 Encyclopædia Britannica/Arrant

ARRANT (a variant of “errant,” from Lat. errare, to wander), a word at first used in its original meaning of wandering, as in “knight-errant,” thus an arrant or itinerant preacher, an arrant thief, one outlawed and wandering at large; the meaning easily passed to that of self-declared, notorious, and by the middle of the 16th century was confined, as an intensive adjective, to words of opprobrium and abuse, an arrant coward meaning thus a self-declared, downright coward.