The Collaborative International Dictionary of English v.0.48:

Pugging \Pug"ging\, n. [See Pug, v. t.]
   1. The act or process of working and tempering clay to make
      it plastic and of uniform consistency, as for bricks, for
      pottery, etc.
      [1913 Webster]

   2. (Arch.) Mortar or the like, laid between the joists under
      the boards of a floor, or within a partition, to deaden
      sound; -- in the United States usually called deafening.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Deafen \Deaf"en\, v. t. [imp. & p. p. Deafened; p. pr. & vb.
   n. Deafening.] [From Deaf.]
   1. To make deaf; to deprive of the power of hearing; to
      render incapable of perceiving sounds distinctly.
      [1913 Webster]

            Deafened and stunned with their promiscuous cries.
                                                  --Addison.
      [1913 Webster]

   2. (Arch.) To render impervious to sound, as a partition or
      floor, by filling the space within with mortar, by lining
      with paper, etc.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

deafening \deaf"en*ing\, n.
   The act or process of rendering impervious to sound, as a
   floor or wall; also, the material with which the spaces are
   filled in this process; pugging; sound insulation.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

deafening \deaf"en*ing\, a.
   extremely loud; so loud as to cause deafness; as, a disco
   with rock music played at a deafening volume.
   [PJC]

WordNet (r) 3.0 (2006):

deafening
    adj 1: loud enough to cause (temporary) hearing loss [syn:
           deafening, earsplitting, thunderous, thundery]

Moby Thesaurus II by Grady Ward, 1.0:

29 Moby Thesaurus words for "deafening":
   booming, ear-piercing, ear-rending, ear-splitting, earthshaking,
   forte, fortissimo, full, intense, loud, loud-sounding, loudish,
   pealing, penetrating, piercing, plangent, pungent, reeking,
   resounding, ringing, sonorous, stentoraphonic, stentorian,
   stentorious, thundering, thunderous, tonitruant, tonitruous,
   window-rattling