The Collaborative International Dictionary of English v.0.48:

Hernia \Her"ni*a\, n.; pl. E. Hernias, L. Herni[ae]. [L.]
   (Med.)
   A protrusion, consisting of an organ or part which has
   escaped from its natural cavity, and projects through some
   natural or accidental opening in the walls of the latter; as,
   hernia of the brain, of the lung, or of the bowels. Hernia of
   the abdominal viscera in most common. Called also rupture.
   [1913 Webster]

   Strangulated hernia, a hernia so tightly compressed in some
      part of the channel through which it has been protruded as
      to arrest its circulation, and produce swelling of the
      protruded part. It may occur in recent or chronic hernia,
      but is more common in the latter.
      [1913 Webster]

WordNet (r) 3.0 (2006):

hernia
    n 1: rupture in smooth muscle tissue through which a bodily
         structure protrudes [syn: hernia, herniation]