Simple Definition of infectious
: capable of causing infection
: capable of being passed to someone else by germs that enter the body
: suffering from a disease that can be spread to other people by germs
Full Definition of infectious
Examples of infectious
viruses and other infectious agents
She has an infectious grin.
First Known Use of infectious
Medical Definition of infectious
1: capable of causing infection <a carrier remains infectious without exhibiting signs of disease> <viruses and other infectious agents>
2: communicable by invasion of the body of a susceptible organism <all contagious diseases are also infectious, but it does not follow that all infectious diseases are contagious—W. A. Hagan>—compare contagious 1
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