Notoriously or preeminently bad; thorough or downright, in a bad sense; shameless; unmitigated; as, an arrant rogue or coward. I discover an arrant laziness in my soul. (Fuller)
2. Thorough or downright, in a good sense. An arrant honest woman. (Burton)
Origin: oe. Erraunt, errant, errand, equiv. To E. Errant wandering, which was first applied to vagabonds, as an errant rogue, an errant thief, and hence passed gradually into its present and worse sense.