Infections are what happens when germs invade your body and cause a disease. Some, like meningitis, an infection of the tissues covering the brain and spinal cord, can be deadly. Others, like the common cold, are relatively mild.

If you've ever scraped your knee and ended up with a swollen, achy scab, you know that you can develop an infection if you don't tend to your cuts and wounds and keep them clean. Though the word was traditionally used in the medical sense to refer to the pathogens, or germs, that cause illness, infection is now sometimes used in a broader sense to refer to people or things that act like pathogens. If rival gangs turn a neighborhood into a battleground, you could refer to this as an infection of gang activity.

Definitions of infection
  1. noun
    (medicine) the invasion of the body by pathogenic microorganisms and their multiplication which can lead to tissue damage and disease
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    (medicine) the development and spread of an infectious disease (especially one caused by a fungus)
    fungal infection, mycosis
    an inflammatory condition caused by a fungus
    type of:
    pathologic process, pathological process
    an organic process occurring as a consequence of disease
  2. noun
    an incident in which an infectious disease is transmitted
    synonyms: contagion, transmission
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    type of:
    a single distinct event
  3. noun
    the pathological state resulting from the invasion of the body by pathogenic microorganisms
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    an infestation with or a resulting infection caused by the pinworm Enterobius vermicularis; occurs especially in children
    felon, whitlow
    a purulent infection at the end of a finger or toe in the area surrounding the nail
    focal infection
    bacterial infection limited to a specific organ or region especially one causing symptoms elsewhere
    cross infection, nonsocial infection
    an infection that is acquired at a hospital or other healthcare facility
    opportunistic infection
    any infection caused by a microorganism that does not normally cause disease in humans; occurs in persons with abnormally functioning immune systems (as AIDS patients or transplant patients receiving immunosuppressive drugs)
    infection in the tissues adjacent to a nail on a finger or toe
    protozoal infection
    any infection caused by a protozoan
    respiratory infection, respiratory tract infection
    any infection of the respiratory tract
    itch, scabies
    a contagious skin infection caused by the itch mite; characterized by persistent itching and skin irritation
    bilharzia, bilharziasis, schistosomiasis
    an infestation with or a resulting infection caused by a parasite of the genus Schistosoma; common in the tropics and Far East; symptoms depend on the part of the body infected
    the presence of pus-forming bacteria or their toxins in the blood or tissues
    an open skin infection
    staphylococcal infection
    an infection with staphylococcus bacteria; usually marked by abscess formation
    septic sore throat, strep throat, streptococcal sore throat, streptococcus tonsilitis, throat infection
    an infection of the oral pharynx and tonsils by streptococcus
    eye infection, hordeolum, sty, stye
    an infection of the sebaceous gland of the eyelid
    infection that occurs while you are being treated for another infection
    secondary infection caused by an opportunistic infection
    tapeworm infection
    intestinal infection by a species of parasitic tapeworm; usually the result of eating inadequately cooked meat or fish
    lockjaw, tetanus
    an acute and serious infection of the central nervous system caused by bacterial infection of open wounds; spasms of the jaw and laryngeal muscles may occur during the late stages
    infection caused by parasites transmitted to humans from infected cats; if contracted by a pregnant woman it can result in serious damage to the fetus
    viral infection, virus infection
    infection by a virus that is pathogenic to humans
    vaccina, vaccinia, variola vaccina, variola vaccine, variola vaccinia
    a local infection induced in humans by inoculation with the virus causing cowpox in order to confer resistance to smallpox; normally lasts three weeks and leaves a pitted scar
    an infective disease caused by sporozoan parasites that are transmitted through the bite of an infected Anopheles mosquito; marked by paroxysms of chills and fever
    progressive vaccinia, vaccinia gangrenosa
    a severe or even fatal form of vaccinia that occurs mainly in persons with an immunological deficiency; characterized by progressive enlargement of the initial lesion
    amebiasis, amebiosis, amoebiasis, amoebiosis
    infection by a disease-causing ameba
    infection of the intestines with protozoa found in contaminated food and water; characterized by diarrhea and nausea and flatulence and abdominal discomfort
    VHF, haemorrhagic fever, hemorrhagic fever, viral haemorrhagic fever, viral hemorrhagic fever
    a group of illnesses caused by a viral infection (usually restricted to a specific geographic area); fever and gastrointestinal symptoms are followed by capillary hemorrhage
    a viral infection (usually in children) marked by sore throat and fever and papules in the mouth and throat and headache and abdominal pain; usually subsides in a short time
    kala azar, leishmaniasis, leishmaniosis
    sores resulting from a tropical infection by protozoa of the genus Leishmania which are spread by sandflies
    lower respiratory infection
    infection of the lower respiratory tract
    infection by the human immunodeficiency virus
    viral pneumonia
    pneumonia caused by a virus
    upper respiratory infection
    infection of the upper respiratory tract
    an opportunistic infection by a fungus of the genus Aspergillus; characterized by inflammation and lesions of the ear and other organs
    boil, furuncle
    a painful sore with a hard core filled with pus
    an inflammatory swelling or sore
    an infection larger than a boil and with several openings for discharge of pus
    a small hard painless nodule at the site of entry of a pathogen (as syphilis)
    fester, suppurating sore
    a sore that has become inflamed and formed pus
    a skin sore caused by chafing
    infection of the vagina
    blood poisoning, septicaemia, septicemia
    invasion of the bloodstream by virulent microorganisms from a focus of infection
    sapraemia, sapremia
    blood poisoning caused by putrefactive bacteria; results from eating putrefied matter
    type of:
    health problem, ill health, unhealthiness
    a state in which you are unable to function normally and without pain
  4. noun
    the communication of an attitude or emotional state among a number of people
    “the infection of his enthusiasm for poetry”
    synonyms: contagion
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    type of:
    something that is communicated by or to or between people or groups
  5. noun
    moral corruption or contamination
    “ambitious men are led astray by an infection that is almost unavoidable”
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    type of:
    corruption, corruptness
    lack of integrity or honesty (especially susceptibility to bribery); use of a position of trust for dishonest gain
  6. noun
    (international law) illegality that taints or contaminates a ship or cargo rendering it liable to seizure
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    type of:
    unlawfulness by virtue of violating some legal statute
  7. noun
    (phonetics) the alteration of a speech sound under the influence of a neighboring sound
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    type of:
    linguistic process
    a process involved in human language
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