infectious

infectious 1 Infectious, contagious, communicable, catchingin their basic use as applied to diseases are distinguishable though closely similar in meaning.

Infectious designates a disease resulting from the invasion of and multiplication in the body by germs (as bacteria, protozoans, or viruses) that produce toxins or destroy or injure tissues.

Contagious more precisely designates an infectious disease caused by receiving living germs directly from a person afflicted with it or by contact with a secretion of his or some object he has touched.

Communicable in this relation is nearly equivalent to infectious, but it emphasizes the transmissibility of the disease rather than the method by which it is acquired.

Catching, a less formal term, is close in meaning to contagious, but it implies even more the dangers of contact.

Infectious, contagious, and catching all have extended use but in such use the fine distinctions exhibited in their technical senses are not carried over with the result that they are nearly exact synonyms meaning rapidly imparted to others; thus, one may speak of contagious, or infectious, enthusiasm or of enthusiasm that is catching

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what a bad temper! I hope it's not catching

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fear is exceedingly infectious: children catch it from their elders even when their elders are not aware of having shown it— Russell

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Analogous words: toxic, mephitic, pestilent, pestilential, virulent, *poisonous

2 Infectious, infective as applied to agents related to the causing of disease may be interchangeable and then mean capable of infecting or tending to infect.

Infectious, however, is more often restricted to the technical and figurative senses expounded in the preceding article.

Infective may be distinctively applied to matter and means potentially infectious

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an infective secretion

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an infective wart

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In extended use it preserves the implication of corruption, strong in infect but often absent in infectious

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infective doctrines

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