— contagiously , adv. — contagiousness, contagiosity /keuhn tay'jee os"i tee/ , n.
/keuhn tay"jeuhs/ , adj.
1. capable of being transmitted by bodily contact with an infected person or object: contagious diseases.
2. carrying or spreading a contagious disease.
3. tending to spread from person to person: contagious laughter.
[ 1350-1400; ME contagiosus, equiv. to contagi ( o ) CONTAGION + -osus -OUS ]
Syn. 1. CONTAGIOUS, INFECTIOUS are usually distinguished in technical medical use. CONTAGIOUS, literally "communicable by contact," describes a very easily transmitted disease as influenza or the common cold. INFECTIOUS refers to a disease involving a microorganism that can be transmitted from one person to another only by a specific kind of contact; venereal diseases are usually infectious. In nontechnical senses, CONTAGIOUS emphasizes the rapidity with which something spreads: Contagious laughter ran through the hall. INFECTIOUS suggests the pleasantly irresistible quality of something: Her infectious good humor made her a popular guest.