Communicable by contagion; that may be imparted by contact or by emanations; catching: as, a contagious disease.Containing or generating contagion; poisonous; pestilential: as, contagious air; contagious clothing.Propagated by influence or incitement; exciting like feeling or action; spreading or liable to spread from one to another: as, contagious example; a contagious speculation.Arising from or due to contagion, in either sense; brought about by propagation or incitement: as, a contagious epidemic.