Search Result for "opsonin": 
Wordnet 3.0

NOUN (1)

1. an antibody in blood serum that attaches to invading microorganisms and other antigens to make them more susceptible to the action of phagocytes; 



WordNet (r) 3.0 (2006):

opsonin
    n 1: an antibody in blood serum that attaches to invading
         microorganisms and other antigens to make them more
         susceptible to the action of phagocytes