late 14c., "infectious disease; contaminated condition;" from Old French infeccion "contamination, poisoning" (13c.) and directly from Late Latin infectionem (nominative infectio), noun of action from past participle stem of Latin inficere (see infect). Meaning "communication of disease by agency of air or water" (distinguished from contagion, which is body-to-body communication), is from 1540s.
infection in·fec·tion (ĭn-fěk'shən)
Invasion by and multiplication of pathogenic microorganisms in a bodily part or tissue, which may produce subsequent tissue injury and progress to overt disease through a variety of cellular or toxic mechanisms.
An instance of being infected.
An agent or a contaminated substance responsible for one's becoming infected.
The pathological state resulting from having been infected.
An infectious disease.
The invasion of the body of a human or an animal by a pathogen such as a bacterium, fungus, or virus. Infections can be localized, as in pharyngitis, or widespread as in sepsis, and are often accompanied by fever and an increased number of white blood cells. Individuals with immunodeficiency syndromes are predisposed to certain infections. See also infectious disease, opportunistic infection.
Invasion of the body or a body part by a pathogenic organism, which multiplies and produces harmful effects on the body's tissues.