1) Antibody 
A precipitin is an antibody which can precipitate out of a solution upon antigen binding. ==Precipitin reaction== The precipitin reaction provided the first quantitative assay for antibody. The precipitin reaction is based upon the interaction of antigen with antibody leading to the production of antigen-antibody complexes. To produce a precipitin...
<protein> Any antibody that forms a precipitating complex (a precipitin line) with an appropriate multivalent antigen. The term is now outmoded. ... (18 Nov 1997) ... 
(pre-sip´ĭ-tin) an antibody to antigen that specifically aggregates the antigen in vivo or in vitro to give a visible precipitate.
An antibody that causes precipitation of soluble antigens.Any antibody that forms a precipitating complex (a precipitin line) with an appropriate multivalent antigen. The term is now outmoded.
Type: Term Pronunciation: prē-sip′i-tin Definitions: 1. An antibody that under suitable conditions combines with and causes its specific and soluble antigen to precipitate from solution. Synonyms: precipitating antibody
[n] - an antibody that causes precipitation when it unites with its antigen
complex lattice of antibody and antigen that becomes too large to stay in solution
noun an antibody that causes precipitation when it unites with its antigen
an antibody that reacts with its specific antigen to form an insoluble precipitate.