Definitions provided by:
Infections and Contagious Diseases Glossary

Terms used to explain Infections and Contagious Diseases can sometimes be confusing. To help you fully understand the articles and features related to this very important health topic, we have compiled a glossary of terms that can help.


Pronunciation: \ˈab-stə-nən(t)s\

Function: noun

1: voluntary forbearance esp. from sexual intercourse or from eating some foods
2: habitual abstaining from intoxicating beverages

Acquired Immunodeficiency Syndrome

acquired immunodeficiency syndrome
Function: noun
: see: aids

Active Immunity

active immunity
Function: noun
: usu. long-lasting immunity that is acquired through production of antibodies within the organism in response to the presence of antigens compare acquired immunity natural immunity passive immunity


Pronunciation: \ə-ˈkyüt\

Function: adjective

1: sensing or perceiving accurately, clearly, effectively, or sensitively <acute vision>
2 a: characterized by sharpness or severity <acute pain> <an acute infection>
b (1): having a sudden onset, sharp rise, and short course <an acute disease> <an acute inflammation> compare chronic 2a
(2): see: acute care<an acute hospital>
c: lasting a short time <acute experiments>


Pronunciation: \-ˌkärs-ən-ˈō-mə\

Function: noun
pl -mas
also -ma*ta
Pronunciation: \-mət-ə\
: a malignant tumor originating in glandular epithelium


Pronunciation: \ˈal-ər-jē\

Function: noun
pl -gies

1: altered bodily reactivity (as hypersensitivity) to an antigen in response to a first exposure <his bee-venom allergy may render a second sting fatal>
2: exaggerated or pathological reaction (as by sneezing, respiratory embarrassment, itching, or skin rashes) to substances, situations, or physical states that are without comparable effect on the average individual
3: medical practice concerned with allergies


Pronunciation: \ˌal-ə-ˈdin-ē-ə\

Function: noun
: pain resulting from a stimulus (as a light touch of the skin) which would not normally provoke pain; also: a condition marked by allodynia


Pronunciation: \-ˈjē-zik, -sik\

Function: adjective
: relating to, characterized by, or producing analgesia


Pronunciation: \ˌant-i-ˈhis-tə-ˌmēn, ˌan-ˌtī-, -mən\

Function: adjective
: tending to block or counteract the physiological action of histamine <human blood lacks antihistamine[1] activity>


Pronunciation: \-ˈvi-rəl\

Function: adjective
: acting, effective, or directed against viruses <antiviral[1] drugs>


Pronunciation: \ˌā-ˌsim(p)-tə-ˈmat-ik\

Function: adjective
: presenting no symptoms of disease <asymptomatic amebiasis>


Pronunciation: \ˈo-ˌtiz-əm\

Function: noun

1: a developmental disorder that appears by age three and that is variable in expression but is recognized and diagnosed by impairment of the ability to form normal social relationships, by impairment of the ability to communicate with others, and by stereotyped behavior patterns esp. as exhibited by a preoccupation with repetitive activities of restricted focus rather than with flexible and imaginative ones

B Cell

B cell
Function: noun
: any of the lymphocytes that have antigen-binding antibody molecules on the surface, that comprise the antibody-secreting plasma cells when mature, and that in mammals differentiate in the bone marrow —called also B lymphocyte, compare t cell

Bacterial Vaginosis

bacterial vag*i*no*sis
Pronunciation: \-ˌvaj-ə-ˈnō-səs\

Function: noun
: vaginitis that is marked by a grayish vaginal discharge usu. of foul odor and that is associated with the presence of a bacterium esp. of the genus Gardnerella (G. vaginalis syn. Haemophilus vaginalis) abbr. BV—called also nonspecific vaginitis


Pronunciation: \ˈbī-ˌäp-sē\

Function: noun
pl -sies
: the removal and examination of tissue, cells, or fluids from the living body

Birth Control

birth control
Function: noun

1: control of the number of children born esp. by preventing or lessening the frequency of conception : see: contraception
2: contraceptive devices or preparations


Pronunciation: \ˈblis-tər\

Function: noun

1: a fluid-filled elevation of the epidermis compare water blister
2: an agent that causes blistering

Booster Shot

booster shot
Function: noun
: a supplementary dose of an immunizing agent —called also booster, booster dose


Pronunciation: \ˈbrest-ˌfēd\

Function: transitive verb
: to feed (a baby) from a mother's breast rather than from a bottle


Pronunciation: \-ō-ˈlīt-əs\

Function: noun
: inflammation of the bronchioles


Pronunciation: \brän-ˈkīt-əs, bräŋ-\
Function: noun
1: acute or chronic inflammation of the bronchial tubes; also: a disease marked by this


Pronunciation: \ˈkan(t)-sər\

Function: noun

1: a malignant tumor of potentially unlimited growth that expands locally by invasion and systemically by metastasis
2: an abnormal state marked by a cancer

Cold Sore

cold sore
Function: noun
: a vesicular lesion that typically occurs in or around the mouth, that initially causes pain, burning, or itching before bursting and crusting over, and that is caused by a herpes simplex virus which remains dormant in the body and may be reactivated by a variety of factors (as stress, fever, or sunburn) —called also fever blister, compare canker sore


Pronunciation: \kə-ˈmyü-ni-kə-bəl\

Function: adjective
: capable of being transmitted from person to person, animal to animal, animal to human, or human to animal : see: transmissible


Pronunciation: \ˈkän-dəm also ˈkən-\

Function: noun

1: a sheath commonly of rubber worn over the penis (as to prevent conception or venereal infection during coitus) —called also sheath
2: a device that is designed to be inserted into the vagina before coitus and that resembles in form and function the condom used by males

Conjugate Vaccine

conjugate vaccine
Function: noun
: a vaccine containing bacterial capsular polysaccharide joined to a protein to enhance immunogenicity; esp: one that is used to immunize infants and children against invasive disease caused by Hib bacteria and that contains the Hib capsular polysaccharide polyribosylribitol phosphate bound to diphtheria or tetanus toxoid or to an outer membrane protein of the meningococcus


Pronunciation: \ˈkrüp\

Function: noun
: inflammation, edema, and subsequent obstruction of the larynx, trachea, and bronchi esp. of infants and young children that is typically caused by a virus and is marked by episodes of difficult breathing and hoarse metallic cough


Pronunciation: \ˌkrī-ō-ˈsərj-(ə-)rē\

Function: noun
pl -ger*ies
: surgery in which diseased or abnormal tissue (as a tumor or wart) is destroyed or removed by freezing (as by the use of liquid nitrogen)


Pronunciation: \ˌdē-kən-ˈjes-tənt\
Function: noun
1: an agent that relieves congestion (as of mucous membranes)

Dental Dam

dental dam
Function: noun
: a rubber dam used in dentistry


Pronunciation: \ˈdər-mə-ˌtōm\

Function: noun

1: an instrument for cutting skin for use in grafting
2: the lateral wall of a somite from which the dermis is produced


Pronunciation: \ˌek-i-ˈnā-sē-ə, -sh(ē-)ə\

Function: noun
: the dried rhizome, roots, or other part of any of three composite herbs (Echinacea angustifolia,E. pallida, and E. purpurea) that were formerly listed in the U.S. Pharmacopeia, that are now used primarily in dietary supplements and herbal remedies, and that are held to stimulate the immune system; also: any of these herbs see purple coneflower


Pronunciation: \ˈep-ə-ˌsōd also -ˌzōd\

Function: noun
: an event that is distinctive and separate although part of a larger series; esp: an occurrence of a usu. recurrent pathological abnormal condition <a manic episode> <hypoglycemic episodes>


Pronunciation: \ik-ˈspek-t(ə-)rənt\

Function: adjective
: having the activity of an expectorant


Pronunciation: \ik-ˈspō-zhər\

Function: noun

1: the fact or condition of being exposed: as
a: the condition of being unprotected esp. from severe weather <the hiker died of exposure after becoming lost in the snowstorm>
b: the condition of being subject to some detrimental effect or harmful condition <repeated exposure to bronchial irritants> <risk exposure to the flu> <benign skin discolorations caused by sun exposure Katie Tyndall>
2: the act or an instance of exposing see indecent exposure

Fallopian Tube

fallopian tube
Function: noun
often cap F: either of the pair of tubes that carry the eggs from the ovary to the uterus —called also uterine tube

Fever Blister

fever blister
Function: noun
: see: cold sore


Pronunciation: \ˈjen-ə-təl\

Function: adjective

1: see: generative
2: of, relating to, or being a sexual organ
3 a: of, relating to, or characterized by the stage of psychosexual development in psychoanalytic theory following the latency period and during which oral and anal impulses are subordinated to adaptive interpersonal mechanisms
b: of, relating to, or characterized by a personality in the genital stage of psychosexual development esp. as typified by normal sexual desires and by concern for the happiness and pleasures of others compare anal 2 oral 3

Genital Herpes

genital herpes
Function: noun
: herpes simplex of the type affecting the genitals —called also herpes genitalis

Genital Wart

genital wart
Function: noun
: a wart on the skin or adjoining mucous membrane usu. near the anus and genital organs —called also condyloma, condyloma acuminatum, venereal wart


Pronunciation: \ˌā-ˌchī-ˈvē\

Function: noun
: any of several retroviruses and esp. HIV-1 that infect and destroy helper T cells of the immune system causing the marked reduction in their numbers that is diagnostic of AIDS —called also AIDS virus, human immunodeficiency virus


Pronunciation: \ˌāch-(ˌ)pē-ˈvē\

Function: noun
: see: human papillomavirus

Hepatitis B

hepatitis B
Pronunciation: \-ˈbē\

Function: noun
: a sometimes fatal hepatitis caused by a double-stranded DNA virus (species Hepatitis B virus of the genus Orthohepadnavirus, family Hepadnaviridae) that tends to persist in the blood serum and is transmitted esp. by contact with infected blood (as by transfusion or by sharing contaminated needles in illicit intravenous drug use) or by contact with other infected bodily fluids (as semen) —called also serum hepatitis


Pronunciation: \ˈhər-(ˌ)pēz\

Function: noun
: any of several inflammatory diseases of the skin caused by herpesviruses and characterized by clusters of vesicles; esp: see: herpes simplex

Herpes Simplex

herpes sim*plex
Pronunciation: \-ˈsim-ˌpleks\

Function: noun
: either of two viral diseases caused by herpesviruses of the genus Simplexvirus that are marked esp. by watery blisters on the skin or mucous membranes of the lips, mouth, face, or genital region see hsv-1 hsv-2

Herpes Zoster

herpes zos*ter
Pronunciation: \-ˈzäs-tər\

Function: noun
: see: shingles

Human Immunodeficiency Virus

human immunodeficiency virus
Function: noun
: see: hiv


Pronunciation: \hyü-ˈmid-ə-ˌfī(-ə)r, yü-\
Function: noun
1: a device for supplying or maintaining humidity

Immune System

immune system
Function: noun
: the bodily system that protects the body from foreign substances, cells, and tissues by producing the immune response and that includes esp. the thymus, spleen, lymph nodes, special deposits of lymphoid tissue (as in the gastrointestinal tract and bone marrow), lymphocytes including the B cells and T cells, and antibodies


Pronunciation: \im-ˈyü-nət-ē\

Function: noun
pl -ties
: the quality or state of being immune; esp: a condition of being able to resist a particular disease esp. through preventing development of a pathogenic microorganism or by counteracting the effects of its products see acquired immunity active immunity natural immunity passive immunity


Pronunciation: \-sə-ˈpresh-ən\

Function: noun
: suppression (as by drugs) of natural immune responses

Incubation Period

incubation period
Function: noun
: the period between the infection of an individual by a pathogen and the manifestation of the disease it causes

Kidney Stone

kidney stone
Function: noun
: a calculus in the kidney —called also renal calculus

Lymph Nodule

lymph nodule
Function: noun
: a small simple lymph node


Pronunciation: \ˈmyü-kəs\

Function: noun
: a viscid slippery secretion that is usu. rich in mucins and is produced by mucous membranes which it moistens and protects

Nervous System

nervous system
Function: noun
: the bodily system that in vertebrates is made up of the brain and spinal cord, nerves, ganglia, and parts of the receptor organs and that receives and interprets stimuli and transmits impulses to the effector organs see autonomic nervous system central nervous system peripheral nervous system


Pronunciation: \ˈaut-ˌbrāk\

Function: noun

1: a sudden rise in the incidence of a disease <an outbreak of measles>
2: a sudden increase in numbers of a harmful organism and esp. an insect within a particular area <an outbreak of locusts>


Function: transitive verb
: to make suffer or cause distress tointransitive verb: to give or have a sensation of pain

Pap Smear

Pap smear
Pronunciation: \ˈpap-\

Function: noun
: a method or a test based on it for the early detection of cancer esp. of the uterine cervix that involves staining exfoliated cells by a special technique which differentiates diseased tissue —called also Papanicolaou smear, Papanicolaou test, Pap test

Passive Immunity

passive immunity
Function: noun
: immunity acquired by transfer of antibodies (as by injection of serum from an individual with active immunity) compare acquired immunity natural immunity


Pronunciation: \ˈpath-ə-jən\

Function: noun
: a specific causative agent (as a bacterium or virus) of disease

Pelvic Inflammatory Disease

pelvic inflammatory disease
Function: noun
: infection of the female reproductive tract (as the fallopian tubes and ovaries) that results from microorganisms (as Neisseria gonorrhea or Chlamydia trachomatis) transmitted esp. during sexual intercourse but also by other means (as during surgery, abortion, or parturition), is marked esp. by lower abdominal pain, an abnormal vaginal discharge, and fever, and is a leading cause of infertility in women abbr. PID


Pronunciation: \n(y)u-ˈmō-nyə\
Function: noun
1: a disease of the lungs that is characterized esp. by inflammation and consolidation of lung tissue followed by resolution, is accompanied by fever, chills, cough, and difficulty in breathing, and is caused chiefly by infection see bronchopneumonia lobar pneumonia primary atypical pneumonia


Pronunciation: \ˈkwor-ən-ˌtēn, ˈkwär-\

Function: noun

1 a: a term during which a ship arriving in port and suspected of carrying contagious disease is held in isolation from the shore
b: a regulation placing a ship in quarantine
c: a place where a ship is detained during quarantine
2 a: a restraint upon the activities or communication of persons or the transport of goods that is designed to prevent the spread of disease or pests
b: a place in which those under quarantine are kept


Function: abbreviation

1 respiratory syncytial virus
2 Rous sarcoma virus


Pronunciation: \ri-ˈkər-ən(t)s, -ˈkə-rən(t)s\

Function: noun

1: return of symptoms of a disease after a remission
2: reappearance of a tumor after previous removal


Pronunciation: \ˈsē-mən\

Function: noun
: a viscid whitish fluid of the male reproductive tract consisting of spermatozoa suspended in secretions of accessory glands (as of the prostate and Cowper's glands)


Pronunciation: \sen-ˈsā-shən, sən-\

Function: noun

1 a: a mental process (as seeing, hearing, or smelling) due to immediate bodily stimulation often as distinguished from awareness of the process compare perception
b: awareness (as of heat or pain) due to stimulation of a sense organ
c: a state of consciousness of a kind usu. due to physical objects or internal bodily changes <a burning sensation in his chest>
2: something (as a physical object, sense-datum, pain, or afterimage) that causes or is the object of sensation

Sexually Transmitted Disease

sexually transmitted disease
Function: noun
: any of various diseases or infections that can be transmitted by direct sexual contact including some (as syphilis, gonorrhea, chlamydia, and genital herpes) chiefly spread by sexual means and others (as hepatitis B and AIDS) often contracted by nonsexual means —called also STD

Sore Throat

sore throat
Function: noun
: painful throat due to inflammation of the fauces and pharynx


Pronunciation: \ˈspər-mə-ˌsīd\

Function: noun
: a preparation or substance (as nonoxynol-9) used to kill sperm —called also spermatocide

Strep Throat

strep throat
Function: noun
: an inflammatory sore throat caused by hemolytic streptococci and marked by fever, prostration, and toxemia —called also septic sore throat, strep sore throat

Swine Flu

swine flu
Function: noun
: see: swine influenza


Pronunciation: \ˈsif-(ə-)ləs\

Function: noun
: a chronic contagious usu. venereal and often congenital disease that is caused by a spirochete of the genus Treponema (T. pallidum) and if left untreated produces chancres, rashes, and systemic lesions in a clinical course with three stages continued over many years —called also lues, see primary syphilis secondary syphilis tertiary syphilis


Function: verb
Pronunciation: \ˈəls-(ə-)riŋ\

: see: ulcerate


Pronunciation: \vak-ˈsēn, ˈvak-ˌ\

Function: noun

1: matter or a preparation containing the virus of cowpox used to vaccinate a person against smallpox
2: a preparation of killed microorganisms, living attenuated organisms, or living fully virulent organisms that is administered to produce or artificially increase immunity to a particular disease <chicken pox vaccine> ; also: a mixture of several such vaccines <measles-mumps-rubella vaccine>


Pronunciation: \ˈvī-rəl\

Function: adjective
: of, relating to, or caused by a virus <viral infections>


Pronunciation: \ˈvəl-və\

Function: noun
pl vul*vae
Pronunciation: \-ˌvē, -ˌvī\
: the external parts of the female genital organs comprising the mons pubis, labia majora, labia minora, clitoris, vestibule of the vagina, bulb of the vestibule, and Bartholin's glands


Pronunciation: \ˈziŋk\

Function: noun
: a bluish white crystalline bivalent metallic element of low to intermediate hardness that is an essential micronutrient for both plants and animals symbol Znsee element table


Pronunciation: \ˈzäs-tər\

Function: noun
: see: shingles

Audio pronunciation for hear it again
Having trouble hearing a pronunciation?
Click here to listen with your default audio player.
© 2011 Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Inc.