1. 
[syn: exasperating, infuriating, maddening, vexing]
The Collaborative International Dictionary of English v.0.48:
Madden \Mad"den\, v. t. [imp. & p. p. Maddened; p. pr. & vb.
   n. Maddening.]
   1. To make mad; to drive to madness; to drive to insanity; to
      craze.
      [1913 Webster]
   2. To make very angry; to enrage; to excite violently with
      passion.
      [1913 Webster]
The Collaborative International Dictionary of English v.0.48:
maddening \maddening\ adj.
   extremely annoying or displeasing.
   Syn: annoying, exasperating, infuriating, vexing.
        [WordNet 1.5]
WordNet (r) 3.0 (2006):
maddening
    adj 1: extremely annoying or displeasing; "his cavelier curtness
           of manner was exasperating"; "I've had an exasperating
           day"; "her infuriating indifference"; "the ceaseless
           tumult of the jukebox was maddening" [syn:
           exasperating, infuriating, maddening, vexing]
Moby Thesaurus II by Grady Ward, 1.0:
47 Moby Thesaurus words for "maddening":
   agitating, breathtaking, charged, cliff-hanging, disquieting,
   distracting, disturbing, electric, exciting, exhilarating,
   galvanic, heady, heart-expanding, heart-stirring, heart-swelling,
   heart-thrilling, impressive, inflammatory, intoxicating, jarring,
   jolting, mind-blowing, moving, overcoming, overmastering,
   overpowering, overwhelming, perturbing, piquant, provocative,
   provoking, ravishing, soul-stirring, spirit-stirring, stimulating,
   stimulative, stirring, striking, suspenseful, suspensive,
   tantalizing, telling, thrilling, thrilly, troubling, unsettling,
   upsetting