colostrum

noun

1. (uncountable, usually)A form of milk produced by the mammary glands in late pregnancy and the few days after giving birth.

   “The researchers isolated the antibodies from the cow's colostrum, the first milk produced after birth, which has very high antibody concentrations. They gave these antibodies, extracted from the colostrum, to 10 volunteers and gave another 10 volunteers extracts from colostrum of cows that were not immunized against the traveler's diarrhea bacteria.”

   “This valuable fluid—colostrum—plays a number of important biological roles, including helping improve an infant's immune system. Nevertheless, many humans intuitively perceive colostrum as “sour milk,” which should not be given to infants. Other species do not make this serious mistake.”

2. (uncountable, usually)A mixture of turpentine and egg yolk, formerly used as an emulsion.