The Collaborative International Dictionary of English v.0.48:

Lorica \Lo*ri"ca\, n.; pl. Loric[ae]. [L., lit., a corselet of
   thongs, fr. lorum thong.]
   1. (Anc. Armor) A cuirass, originally of leather, afterward
      of plates of metal or horn sewed on linen or the like.
      [1913 Webster]

   2. (Chem.) Lute[1] for protecting vessels from the fire.
      [1913 Webster]

   3. (Zool.) The protective case or shell of an infusorian or
      rotifer.
      [1913 Webster]

WordNet (r) 3.0 (2006):

lorica
    n 1: a hard protective sheath (as secreted by certain
         protoctists, for example)