The Collaborative International Dictionary of English v.0.48:

Trichina \Tri*chi"na\ (-n[.a]), n.; pl. Trichinae. [NL., fr.
   Gr. ? hairy, made of hair, fr. tri`x, tricho`s, hair.]
   (Zool.)
   A small, slender nematoid worm (Trichina spiralis) which,
   in the larval state, is parasitic, often in immense numbers,
   in the voluntary muscles of man, the hog, and many other
   animals. When insufficiently cooked meat containing the
   larvae is swallowed by man, they are liberated and rapidly
   become adult, pair, and the ovoviviparous females produce in
   a short time large numbers of young which find their way into
   the muscles, either directly, or indirectly by means of the
   blood. Their presence in the muscles and the intestines in
   large numbers produces trichinosis.
   [1913 Webster]

WordNet (r) 3.0 (2006):

trichina
    n 1: parasitic nematode occurring in the intestines of pigs and
         rats and human beings and producing larvae that form cysts
         in skeletal muscles [syn: trichina, Trichinella
         spiralis]