adj 1  :  active in very small quantities <an germicide>   2 a  :  produced by very small quantities < action of finely divided silver in disinfecting water>   b  :  of or relating to the action of such quantities  3  :  of, relating to, or being produced by the specific activity of an oligodynamic substance <the action of some pyridine derivatives on pathogenic microorganisms>  .
 
 
 
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