Definitions provided by:
Allergies and the Immune System Glossary

Terms used to explain Allergies and the Immune System 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.

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

Allergen

al*ler*gen
Pronunciation: \ˈal-ər-jən\
Function: noun
1: a substance that induces allergy <inhaled allergens> <a suspected food allergen>

Allergy

al*ler*gy
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

Antihistamine

1an*ti*his*ta*mine
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>

Arthritis

ar*thri*tis
Pronunciation: \är-ˈthrīt-əs\


Function: noun
pl -thrit*i*des
Pronunciation: \-ˈthrit-ə-ˌdēz\
: inflammation of joints due to infectious, metabolic, or constitutional causes; also: a specific arthritic condition (as gouty arthritis or psoriatic arthritis)

Atopy

at*o*py
Pronunciation: \ˈat-ə-pē\


Function: noun
pl -pies
: a prob. hereditary allergy characterized by symptoms (as asthma, hay fever, or hives) produced upon exposure esp. by inhalation to the exciting environmental antigen

Autism

au*tism
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

Biopsy

1bi*op*sy
Pronunciation: \ˈbī-ˌäp-sē\


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

Booster Shot

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

Bronchial Tube

bronchial tube
Function: noun
: a primary bronchus; also: any of its branches

Bursitis

bur*si*tis
Pronunciation: \(ˌ)bər-ˈsīt-əs\


Function: noun
: inflammation of a bursa (as of the shoulder or elbow)

Cancer

can*cer
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

Carpal Tunnel Syndrome

carpal tunnel syndrome
Function: noun
: a condition caused by compression of the median nerve in the carpal tunnel and characterized esp. by weakness, pain, and disturbances of sensation in the hand and fingers abbr. CTS

Chemotherapy

che*mo*ther*a*py
Pronunciation: \-ˈther-ə-pē\


Function: noun
pl -pies
: the use of chemical agents in the treatment or control of disease or mental disorder

Communicable

com*mu*ni*ca*ble
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

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

Corticosteroid

cor*ti*co*ste*roid
Pronunciation: \ˌkort-i-kō-ˈsti(ə)r-ˌoid also -ˈste(ə)r-\



Function: noun
: any of various adrenal-cortex steroids (as corticosterone, cortisone, and aldosterone) that are divided on the basis of their major biological activity into glucocorticoids and mineralocorticoids

Dander

dan*der
Pronunciation: \ˈdan-dər\


Function: noun
: see: dandruff; specif: minute scales from hair, feathers, or skin that may act as allergens

Decongestant

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

Differentiation

dif*fer*en*ti*a*tion
Pronunciation: \-ˌren-chē-ˈā-shən\


Function: noun

1 a: the act of describing a thing by giving its differentia
b: the enhancement of microscopically visible differences between tissue or cell parts by partial selective decolorization or removal of excess stain (as in regressive staining)
c: the development of a discriminating conditioned response with a positive response to one stimulus and absence of the response on the application of similar but discriminably different stimuli
2 a: modification of different parts of the body for performance of particular functions; also: specialization of parts or organs in the course of evolution
b: the sum of the developmental processes whereby apparently unspecialized cells, tissues, and structures attain their adult form and function compare determination 2

Dust Mite

dust mite
Function: noun
: any of various mites (esp. family Pyroglyphidae) implicated in human allergic reactions to dust; esp: see: house-dust mite

Eczema

ec*ze*ma
Pronunciation: \ig-ˈzē-mə, ˈeg-zə-mə, ˈek-sə-\


Function: noun
: an inflammatory condition of the skin characterized by redness, itching, and oozing vesicular lesions which become scaly, crusted, or hardened

Elimination

elim*i*na*tion
Pronunciation: \i-ˌlim-ə-ˈnā-shən\


Function: noun

1: the act of discharging or excreting waste products or foreign substances from the body
2eliminationspl: bodily discharges including urine, feces, and vomit
3: the removal from a molecule of the constituents of a simpler molecule <ethylene is formed by the elimination of water from ethanol>

Erythrocyte

eryth*ro*cyte
Pronunciation: \i-ˈrith-rə-ˌsīt\


Function: noun
: see: red blood cell

Exhalation

ex*ha*la*tion
Pronunciation: \ˌeks-(h)ə-ˈlā-shən\


Function: noun

1: the action of forcing air out of the lungs
2: something (as the breath) that is exhaled or given off

Exposure

ex*po*sure
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

Fibromyalgia

fi*bro*my*al*gia
Pronunciation: \ˌfī-(ˌ)brō-ˌmī-ˈal-j(ē-)ə\
Function: noun
1: a chronic disorder characterized by widespread pain, tenderness, and stiffness of muscles and associated connective tissue structures that is typically accompanied by fatigue, headache, and sleep disturbances —called also fibromyalgia syndrome, fibromyositis

HEPA

HEPA
Pronunciation: \ˈhep-ə\


Function: adjective
Etymology: high efficiency particulate air
: being, using, or containing a filter usu. designed to remove 99.97% of airborne particles measuring 0.3 microns or greater in diameter passing through it <HEPA filters> <HEPA vacuum cleaners>

Hay Fever

hay fever
Pronunciation: \ˈhā-ˌfē-vər\


Function: noun
: an acute allergic reaction to pollen that is usu. seasonal and is marked by sneezing, nasal discharge and congestion, and itching and watering of the eyes —called also pollinosis

Hematocrit

he*mat*o*crit
Function: noun

1: an instrument for determining usu. by centrifugation the relative amounts of plasma and corpuscles in blood
2: the percent of the volume of whole blood that is composed of red blood cells as determined by separation of red blood cells from the plasma usu. by centrifugation <a hematocrit ranging from 42% to 52% in males and 35% to 47% in females is typically considered normal> —called also packed cell volume

Histamine

his*ta*mine
Pronunciation: \ˈhis-tə-ˌmēn, -mən\


Function: noun
: a compound C5H9N3 esp. of mammalian tissues that causes dilatation of capillaries, contraction of smooth muscle, and stimulation of gastric acid secretion, that is released during allergic reactions, and that is formed by decarboxylation of histidine

Hives

hives
Pronunciation: \ˈhīvz\


Function: noun plural but singular or plural in construction
: an allergic disorder marked by raised edematous red patches of skin or mucous membrane and usu. by intense itching and caused by contact with a specific precipitating factor (as a food, drug, or inhalant) either externally or internally —called also urticaria

Hygiene

hy*giene
Pronunciation: \ˈhī-ˌjēn also hī-ˈ\


Function: noun

1: a science of the establishment and maintenance of health see industrial hygiene mental hygiene
2: conditions or practices (as of cleanliness) conducive to health

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

Immunosuppression

im*mu*no*sup*pres*sion
Pronunciation: \-sə-ˈpresh-ən\


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

Immunotherapy

im*mu*no*ther*a*py
Pronunciation: \-ˈther-ə-pē\


Function: noun
pl -pies
: treatment of or prophylaxis against disease by attempting to produce active or passive immunity —called also immune therapy

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

Inhaler

in*hal*er
Pronunciation: \in-ˈhā-lər\
Function: noun
1: a device by means of which usu. medicinal material is inhaled compare inhalator

Learn more: Using Inhalers
Irritant

1ir*ri*tant
Pronunciation: \ˈir-ə-tənt\


Function: adjective
: causing irritation; specif: tending to produce inflammation

Leukotriene

leu*ko*tri*ene
Pronunciation: \ˌlü-kə-ˈtrī-ˌēn\


Function: noun
: any of a group of eicosanoids that are generated in basophils, mast cells, macrophages, and human lung tissue by lipoxygenase-catalyzed oxygenation esp. of arachidonic acid and that participate in allergic responses (as bronchoconstriction in asthma) see slow-reacting substance of anaphylaxis

Lupus

lu*pus
Pronunciation: \ˈlü-pəs\
Function: noun
1: any of several diseases (as lupus vulgaris or systemic lupus erythematosus) characterized by skin lesions

Lymph

lymph
Pronunciation: \ˈlim(p)f\


Function: noun
: a usu. clear coagulable fluid that passes from intercellular spaces of body tissue into the lymphatic vessels, is discharged into the blood by way of the thoracic duct and right lymphatic duct, and resembles blood plasma in containing white blood cells and esp. lymphocytes but normally few red blood cells and no platelets see chyle compare cerebrospinal fluid

Lymph System

lymph system
Function: noun
: see: lymphatic system

Lymphatic System

lymphatic system
Function: noun
: the part of the circulatory system that is concerned esp. with scavenging fluids and proteins that have escaped from cells and tissues and returning them to the blood, with the phagocytic removal of cellular debris and foreign material, and with immune responses, that overlaps and parallels the system of blood vessels in function and shares some constituents with it, and that consists esp. of the thymus, spleen, tonsils, lymph, lymph nodes, lymphatic vessels, lymphocytes, and bone marrow where stem cells differentiate into precursors of B cells and T cells —called also lymphoid system, lymph system

Lymphoma

lym*pho*ma
Pronunciation: \lim-ˈfō-mə\


Function: noun
pl -mas
also -ma*ta
Pronunciation: \-mət-ə\
: a usu. malignant tumor of lymphoid tissue

Mast Cell

mast cell
Pronunciation: \ˈmast-\


Function: noun
: a granulocyte that occurs esp. in connective tissue and has basophilic granules containing substances (as histamine and heparin) which mediate allergic reactions

Mucus

mu*cus
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

Musculoskeletal

mus*cu*lo*skel*e*tal
Pronunciation: \ˌməs-kyə-lō-ˈskel-ət-əl\


Function: adjective
: of, relating to, or involving both musculature and skeleton <musculoskeletal defects> <the musculoskeletal organization of the arm>

Myositis

myo*si*tis
Pronunciation: \ˌmī-ə-ˈsīt-əs\


Function: noun
: muscular discomfort or pain from infection or an unknown cause

Nausea

nau*sea
Pronunciation: \ˈno-zē-ə, -sē-ə; ˈno-zhə, -shə\


Function: noun
: a stomach distress with distaste for food and an urge to vomit

Nebulizer

neb*u*liz*er
Function: noun
: see: atomizer; specif: an atomizer equipped to produce an extremely fine spray for deep penetration of the lungs

Neutropenia

neu*tro*pe*nia
Pronunciation: \ˌn(y)ü-trə-ˈpē-nē-ə\


Function: noun
: leukopenia in which the decrease in white blood cells is chiefly in neutrophils

Osteophyte

os*teo*phyte
Pronunciation: \ˈäs-tē-ə-ˌfīt\


Function: noun
: a pathological bony outgrowth

Osteoporosis

os*teo*po*ro*sis

Function: noun
pl -ro*ses

: a condition that affects esp. older women and is characterized by decrease in bone mass with decreased density and enlargement of bone spaces producing porosity and brittleness

Paresthesia

par*es*the*sia
Function: noun
: a sensation of pricking, tingling, or creeping on the skin having no objective cause and usu. associated with injury or irritation of a sensory nerve or nerve root

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

Patch Test

patch test
Function: noun
: a test for determining allergic sensitivity that is made by applying to the unbroken skin small pads soaked with the allergen to be tested and that indicates sensitivity when irritation develops at the point of application compare intradermal test prick test scratch test

Pathogen

patho*gen
Pronunciation: \ˈpath-ə-jən\


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

Pathologist

pa*thol*o*gist
Pronunciation: \pə-ˈthäl-ə-jəst, pa-\


Function: noun
: a specialist in pathology; specif: a physician who interprets and diagnoses the changes caused by disease in tissues and body fluids

Peak Flow Meter

peak flow meter
Pronunciation: \ˌpēk-ˈflō-\


Function: noun
: a device that measures the maximum rate of air flow out of the lungs during forced expiration and that is used esp. for monitoring lung capacity of individuals with asthma (as to indicate bronchial narrowing) —called also peak expiratory flow meter

Plasma Cell

plasma cell
Function: noun
: a lymphocyte that is a mature antibody-secreting B cell

Pollen

pol*len
Pronunciation: \ˈpäl-ən\


Function: noun
: a mass of male spores in a seed plant appearing usu. as a fine dust

Prednisone

pred*ni*sone
Pronunciation: \ˈpred-nə-ˌsōn also -ˌzōn\


Function: noun
: a glucocorticoid C21H26O5 that is a dehydrogenated analog of cortisone and is used as an anti-inflammatory agent, as an antineoplastic agent, and as an immunosuppressant

Prick Test

prick test
Pronunciation: \ˈprik-\


Function: noun
: a test for allergic susceptibility made by placing a drop of the allergy-producing substance on the skin and making breaks in the skin by lightly pricking the surface (as with a pin) compare intradermal test patch test scratch test

Psoriatic Arthritis

psoriatic arthritis
Function: noun
: a severe form of arthritis accompanied by inflammation, psoriasis of the skin or nails, and a negative test for rheumatoid factor —called also psoriasis arthropathica

Quarantine

1quar*an*tine
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

Radiation Therapy

radiation therapy
Function: noun
: see: radiotherapy

Reactive Arthritis

reactive arthritis
Function: noun
: acute arthritis that sometimes develops following a bacterial infection (as with the bacteria of the genera Shigella, Salmonella, or Chlamydia)

Remission

re*mis*sion
Pronunciation: \ri-ˈmish-ən\


Function: noun
: a state or period during which the symptoms of a disease are abated <cancer in remission after treatment> compare arrest cure 1 intermission

Rheumatism

rheu*ma*tism
Pronunciation: \ˈrü-mə-ˌtiz-əm, ˈrum-ə-\


Function: noun

1: any of various conditions characterized by inflammation or pain in muscles, joints, or fibrous tissue <muscular rheumatism>
2: see: rheumatoid arthritis

Rhinitis

rhi*ni*tis
Pronunciation: \rī-ˈnīt-əs\


Function: noun
pl -nit*i*des
Pronunciation: \-ˈnit-ə-ˌdēz\
: inflammation of the mucous membrane of the nose marked esp. by rhinorrhea, nasal congestion and itching, and sneezing; also: any of various conditions characterized by rhinitis see allergic rhinitis rhinitis medicamentosa rhinitis sicca vasomotor rhinitis

Sputum

spu*tum
Pronunciation: \ˈsp(y)üt-əm\


Function: noun
pl spu*ta
Pronunciation: \-ə\
: the matter discharged from the air passages in diseases of the lungs, bronchi, or upper respiratory tract that contains mucus and often pus, blood, fibrin, or bacterial products

Stem Cell

stem cell
Pronunciation: \ˈstem-\


Function: noun
: an unspecialized cell that gives rise to differentiated cells <hematopoietic stem cells in bone marrow>

Steroid

ste*roid
Pronunciation: \ˈsti(ə)r-ˌoid also ˈste(ə)r-\



Function: noun
: any of numerous natural or synthetic compounds containing a 17-carbon 4-ring system and including the sterols and various hormones and glycosides see anabolic steroid

Tendinitis

ten*di*ni*tis
Function: noun
: inflammation of a tendon

Theophylline

the*oph*yl*line
Pronunciation: \thē-ˈäf-ə-lən\


Function: noun
: a feebly basic bitter crystalline compound C7H8N4O2 that is present in small amounts in tea but is prepared chiefly by synthesis, that is isomeric with theobromine, and that is used in medicine often in the form of derivatives or in combination with other drugs esp. as a bronchodilator to relieve or prevent symptoms of asthma and bronchospasm associated with chronic bronchitis and emphysema

Thrombocyte

throm*bo*cyte
Pronunciation: \-bə-ˌsīt\


Function: noun
: see: platelet

Tissue

tis*sue
Pronunciation: \ˈtish-(ˌ)ü, ˈtish-ə(-w), chiefly Brit ˈtis-(ˌ)yü\


Function: noun
: an aggregate of cells usu. of a particular kind together with their intercellular substance that form one of the structural materials of a plant or an animal and that in animals include connective tissue, epithelium, muscle tissue, and nerve tissue

Tomography

to*mog*ra*phy
Pronunciation: \tō-ˈmäg-rə-fē\


Function: noun
pl -phies
: a method of producing a three-dimensional image of the internal structures of a solid object (as the human body) by the observation and recording of the differences in the effects on the passage of waves of energy impinging on those structures —called also stratigraphy, see computed tomography positron-emission tomography

Wheeze

1wheeze
Pronunciation: \ˈhwēz, ˈwēz\



Function: intransitive verb
wheezed
wheez*ing
: to breathe with difficulty usu. with a whistling sound

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.