n 1 a  :  the causative agent of an infectious disease  b  :  any of a large group of submicroscopic infective agents that are regarded either as extremely simple microorganisms or as extremely complex molecules, that typically contain a protein coat surrounding an RNA or DNA core of genetic material but no semipermeable membrane, that are capable of growth and multiplication only in living cells, and that cause various important diseases in humans, animals, or plants : also  :  FILTERABLE VIRUS  c  :  a disease caused by a virus  2  :  an antigenic but not infective material (as vaccine lymph) obtainable from a case of an infectious disease .
 
 
 
Similar sounding terms:  far·cy  fer·rous  forcé  fraise 
 
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