Con-tā'giōus, a.
a. [Lat. contagiosus, Fr. contagieux, Pr. contagios, Sp., Pg., & It. contagioso.]
Sense 1. (Med.) Communicable by contact; catching; as, a contagious disease.
Sense 2. Containing or generating contagion; pestilential; as, contagious air.
Sense 3. Spreading or communicable from one to another.
His genius rendered his courage more contagious. Wirt.
The spirit of imitation is contagious. Fisher Ames.
Synonyms—CONTAGIOUS, INFECTIOUS. 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, &c.; while an infectious disease supposes some entirely different cause acting by a hidden influence, like the miasma of prison ships, of marshes, &c., 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; the contagion of bad example, the contagion of fear, &c., when we refer to transmission by proximity or contact. On the other hand, we speak of infection by bad principles, &c., when we consider any thing as diffused abroad by some hidden influence.