The Collaborative International Dictionary of English v.0.48:

Viscera \Vis"ce*ra\, n.,
   pl. of Viscus.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Viscus \Vis"cus\, n.; pl. Viscera. [L., perhaps akin to E.
   viscid.] (Anat.)
   One of the organs, as the brain, heart, or stomach, in the
   great cavities of the body of an animal; -- especially used
   in the plural, and applied to the organs contained in the
   abdomen.
   [1913 Webster]

WordNet (r) 3.0 (2006):

viscera
    n 1: internal organs collectively (especially those in the
         abdominal cavity); "`viscera' is the plural form of
         `viscus'" [syn: viscera, entrails, innards]

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "viscera":
   abdomen, anus, appendix, being, blind gut, bones, bosom, bowels,
   brain, breast, cecum, colon, duodenum, endocardium, entrails,
   esprit, foregut, giblets, gizzard, guts, heart, heart of hearts,
   heartstrings, hindgut, inmost heart, inmost soul, innards,
   inner mechanism, innermost being, insides, internals, intestine,
   inwards, jejunum, kidney, kishkes, large intestine, liver,
   liver and lights, lung, midgut, perineum, pump, pylorus, rectum,
   secret places, small intestine, soul, spirit, spleen, stomach,
   stuffing, ticker, tripes, vermiform appendix, vitals, works