The Collaborative International Dictionary of English v.0.48:

Transfusion \Trans*fu"sion\, n. [L. transfusio: cf. F.
   transfusion.]
   1. The act of transfusing, or pouring, as liquor, out of one
      vessel into another. --Howell.
      [1913 Webster]

   2. (Med.) The act or operation of transferring the blood of
      one man or animal into the vascular system of another;
      also, the introduction of any fluid into the blood
      vessels, or into a cavity of the body from which it can
      readily be adsorbed into the vessels; intrafusion; as, the
      peritoneal transfusion of milk.
      [1913 Webster]

WordNet (r) 3.0 (2006):

transfusion
    n 1: the introduction of blood or blood plasma into a vein or
         artery [syn: transfusion, blood transfusion]
    2: the action of pouring a liquid from one vessel to another