The Collaborative International Dictionary of English v.0.48:

Colostrum \Co*los"trum\, n. [L., biestings.] (Med.)
      (a) The first milk secreted after delivery; biestings.
      (b) A mixture of turpentine and the yolk of an egg,
          formerly used as an emulsion.
          [1913 Webster]

WordNet (r) 3.0 (2006):

colostrum
    n 1: milky fluid secreted for the first day or two after
         parturition [syn: colostrum, foremilk]