The Collaborative International Dictionary of English v.0.48:

Entrails \En"trails\, n. pl. [F. entrailles, LL. intralia,
   intranea, fr. interaneum, pl. interanea, intestine,
   interaneus inward, interior, fr. inter between, among,
   within. See Internal.]
   1. The internal parts of animal bodies; the bowels; the guts;
      viscera; intestines.
      [1913 Webster]

   2. The internal parts; as, the entrails of the earth.
      [1913 Webster]

            That treasure . . . hid the dark entrails of
            America.                              --Locke.
      [1913 Webster]

WordNet (r) 3.0 (2006):

entrails
    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:

46 Moby Thesaurus words for "entrails":
   abdomen, anus, appendix, blind gut, bowels, brain, cecum, colon,
   duodenum, endocardium, foregut, giblets, gizzard, guts, heart,
   hindgut, innards, inner mechanism, insides, internals, intestine,
   intestines, inwards, jejunum, kidney, kishkes, large intestine,
   liver, liver and lights, lung, midgut, perineum, pluck, pump,
   pylorus, rectum, small intestine, spleen, stomach, stuffing,
   ticker, tripes, vermiform appendix, viscera, vitals, works