Found one definition

  1.                 From WordNet dictionary, version 3.0:
                    

    arrant s. 1. without qualification; used informally as (often pejorative) intensifiers; "an arrant fool"; "a complete coward"; "a consummate fool"; "a double-dyed villain"; "gross negligence"; "a perfect idiot"; "pure folly"; "what a sodding mess"; "stark staring mad"; "a thoroughgoing villain"; "utter nonsense"; "the unadulterated truth" Synonyms: arrant(a), complete(a), consummate(a), double-dyed(a), everlasting(a), gross(a), perfect(a), pure(a), sodding(a), stark(a), staring(a), thoroughgoing(a), utter(a), unadulterated