\Con*ta"gious\, a. [L. contagiosus: cf. F.
contagieux.]
1. (Med.) Communicable by contact, by a virus, or by a bodily
   exhalation; catching; as, a contagious disease.
2. Conveying or generating disease; pestilential; poisonous;
   as, contagious air.
3. Spreading or communicable from one to another; exciting
   similar emotions or conduct in others.
         His genius rendered his courage more contagious.
                                               --Wirt.
         The spirit of imitation is contagious. --Ames.
Syn: {Contagious}, {Infectious}.
Usage: These words have been used in very diverse senses;
       but, in general, a contagious disease has been
       considered as one which is caught from another by
       contact, by the breath, by bodily effluvia, etc.;
       while an infectious disease supposes some entirely
       different cause acting by a hidden influence, like the
       miasma of prison ships, of marshes, etc., infecting
       the system with disease. ``This distinction, though
       not universally admitted by medical men, as to the
       literal meaning of the words, certainly applies to
       them in their figurative use. Thus we speak of the
       contagious influence of evil associates; their
       contagion of bad example, the contagion of fear, etc.,
       when we refer to transmission by proximity or contact.
       On the other hand, we speak of infection by bad
       principles, etc., when we consider anything as
       diffused by some hidden influence.