The Collaborative International Dictionary of English v.0.48:

Visceral \Vis"cer*al\, a. [Cf. F. visc['e]ral, LL. visceralis.]
   1. (Anat.) Of, pertaining to, or affecting the viscera;
      splanchnic.
      [1913 Webster]

   2. Fig.: Having deep sensibility. [R.] --Bp. Reynolds.
      [1913 Webster]

   3. proceeding from emotion or instinct rather than from
      intellect; deeply emotional; -- as, a visceral reaction.
      [PJC]

   4. dealing with coarse or base emotions; -- as, a visceral
      literary style. --[RHUD]
      [PJC]

   Visceral arches (Anat.), the bars or ridges between the
      visceral clefts.

   Visceral cavity or Visceral tube (Anat.), the ventral
      cavity of a vertebrate, which contains the alimentary
      canal, as distinguished from the dorsal, or
      cerebro-spinal, canal.

   Visceral clefts (Anat.), transverse clefts on the sides
      just back of the mouth in the vertebrate embryo, which
      open into the pharyngeal portion of the alimentary canal,
      and correspond to the branchial clefts in adult fishes.
      [1913 Webster]

WordNet (r) 3.0 (2006):

visceral
    adj 1: relating to or affecting the viscera; "visceral
           bleeding"; "a splanchnic nerve" [syn: visceral,
           splanchnic]
    2: obtained through intuition rather than from reasoning or
       observation [syn: intuitive, nonrational, visceral]

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "visceral":
   abdominal, affectional, affective, anal, appendical, cardiac,
   cecal, colic, colonic, coronary, demonstrative, duodenal,
   emotiometabolic, emotiomotor, emotional, emotiovascular, emotive,
   enteric, feeling, gastric, glandular, gut, ileac, instinctual,
   interior, internal, intestinal, intimate, intuitive, jejunal,
   mesogastric, of soul, overdemonstrative, pyloric, rectal, soulful,
   splanchnic