contagion contagion /kənˈteɪdʒən/

noun

1. The communication of an attitude or emotional state among a number of people  ( contagion , infection )
   the communication of an attitude or emotional state among a number of people
    A contagion of mirth
   a contagion of mirth
    The infection of his enthusiasm for poetry
   the infection of his enthusiasm for poetry
   
2. An incident in which an infectious disease is transmitted  ( contagion , infection , transmission )
   an incident in which an infectious disease is transmitted
   
3. Any disease easily transmitted by contact  ( contagion , contagious disease )
   any disease easily transmitted by contact