medium

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medium

 [me´de-um] (pl. mediums, me´dia) (L.)
1. an agent by which something is accomplished or an impulse is transmitted.
3. a preparation used in treating histologic specimens.
contrast medium a radiopaque substance used in radiography to permit visualization of body structures. Called also contrast agent.
culture medium a substance or preparation used to support the growth of microorganisms or other cells; called also medium.
dioptric media refracting media.
disperse medium dispersive m.
dispersion medium dispersive m.
dispersive medium the continuous phase of a colloid system; the medium in which the particles of the disperse phase are distributed, corresponding to the solvent in a true solution.
refracting media the transparent tissues and fluid in the eye through which light rays pass and by which they are refracted and brought to a focus on the retina.

me·di·um

, pl.

me·di·a

(mē'dē-yŭm, -ă),
1. A means; that through or by which an action is performed.
2. A substance through which impulses or impressions are transmitted.
3. Synonym(s): culture medium
4. The liquid holding a substance in solution or suspension.
5. Any of the substances in which a chromatographic or electrophoretic separation is effected.
[L. neuter of medius, middle]

medium

/me·di·um/ (me´de-um) pl. mediums, me´dia   [L.]
1. a substance that transmits impulses.
2. culture medium; see under C.
3. a preparation used in treating histologic specimens.

active medium  the aggregated atoms, ions, or molecules contained in a laser's optical cavity, in which stimulated emission will occur under the proper excitation.
clearing medium  a substance to render histologic specimens transparent.
contrast medium  a radiopaque substance used in radiography to permit visualization of internal body structures.
culture medium  see under C.
dioptric media  refracting media.
disperse medium , dispersion medium, dispersive medium the continuous phase of a colloid system; the medium in which the particles of the disperse phase are distributed, analogous to the solvent in a true solution.
nutrient medium  a culture medium to which nutrient materials have been added.
refracting media  the transparent tissues and fluid in the eye through which light rays pass and by which they are refracted and focused on the retina.

medium

(mē′dē-əm)
n. pl. me·dia (-dē-ə) or me·diums
1. Something, such as an intermediate course of action, that occupies a position or represents a condition midway between extremes.
2. An intervening substance through which something else is transmitted or carried on.
3. pl. media
a. A surrounding environment in which something functions and thrives.
b. The substance in which a specific organism lives and thrives.
c. A culture medium.

medium

[mē′dē·əm] pl. media
Etymology: L, medius, middle
a substance through which something moves or through which it acts. A contrast medium is a substance that has a density different from that of body tissues, permitting visual comparison of structures when used with imaging techniques such as x-ray film. A culture medium is a substance that provides a nutritional environment for the growth of microorganisms or cells. A dispersion medium is the substance in which a colloid is dispersed. A refractory medium is the transparent tissues and fluid of the eye that refract light.

medium

Imaging
A substance used to enhance imaging of a particular structure.
 
Informatics
A material on which data is stored.

Microbiology
A liquid or solid matrix with nutrient designed to support the growth of microorganisms.

Medium types (microbiology)
Differential medium
Often solid and contains various chemical and other substances, e.g., colourants that may be produced by certain microorganisms, aiding in their identification.

Enrichment medium
Often liquid and contains specific nutrients to give one or more of the microorganisms a growth advantage.
 
Selective medium
Those in which nutrients are added to either promote the growth of one or more group of bacteria, or inhibitors (e.g., nalidixic acid, malachite green and others) to slow the growth of certain bacteria, giving the desired organisms a “selective” growth advantage.
 
Molecular biology
A gel on which a reaction can occur.
 
Paranormal
Channeler, see there.

medium

Imaging A substance used to enhance imaging of a particular structure. See Contrast medium, High-osmolality contrast medium, Low-osmolality contrast medium, Informatics A material on which data is stored. See Magnetic medium, Multimedia, Output medium.

me·di·um

, pl. media (mē'dē-ŭm, -ă)
1. A means; that through which an action is performed.
2. A substance through which impulses or impressions are transmitted.
3. Synonym(s): culture medium.
4. The liquid holding a substance in solution or suspension.

medium

Any substance in which micro-organisms may be cultured in an incubator. Most culture media use AGAR jelly or gelatine containing additional materials such as blood or meat broth to encourage bacterial growth. Selective media contain substances that discourage the growth of unwanted organisms or specifically foster the growth of others.

medium

(pl. media) a substance on which microorganisms, other small organisms, cells and tissues can be cultured. A medium can be liquid or solid. If solid, it frequently contains AGAR, a stiffening agent extracted from seaweed. Culture media can contain all necessary nutrients and trace elements for normal growth (a minimal medium) but can also be supplemented. For example, ANTIBIOTICS can be added to test for antibiotic resistance in bacteria.

me·di·um

, pl. media (mē'dē-ŭm, -ă)
1. A means; that through or by which an action is performed.
2. Liquid holding another substance in solution or suspension.

medium (mē´dēum),

n an interposed agent or material; a carrier; a material serving as an environment for the growth of microorganisms.
medium, computer,
n the material on which data are recorded (e.g., CD-RWs, DVDs, external hard drives, magnetic tape).
medium, marking,
n 1. an agent, such as carbon paper or inked ribbon, used to indicate an occlusal interference.
n 2. an agent, such as stencil correction fluid, rouge and alcohol, or pressure indicator paste, used to determine areas of interference or pressure related to a removable prosthesis.
medium, radiopaque,
n a substance that may be injected into a cavity or region to increase its density in radiographic examination and thereby aid in diagnosis. Lipiodol, Iodochloral, Parabodril, and Ioduron are examples of such materials.
medium, Sabouraud's,
n.pr a nutrient agar used to grow fungi. It is especially useful for the growth and identification of
C. albicans, the causative agent of thrush.
medium, separating,
n a coating that is used on a surface and serves to prevent another surface or material from adhering to the first (e.g., tinfoil, cellophane, or alginate, all of which are used to protect an acrylic resin from the moisture in the gypsum mold).

medium

pl. media, mediums [L.]
1. an agent by which something is accomplished or an impulse is transmitted.
2. a substance providing the proper nutritional environment for the growth of microorganisms; called also culture medium.

basic nutritive medium
one adequate for the growth requirements of most bacteria.
contrast medium
a radiopaque (positive) substance, or (negative) gases used in radiography to permit visualization of body structures.
culture medium
a substance used to support the growth of microorganisms or other cells.
dioptric medium
refracting medium (see below).
disperse medium, dispersion medium
the continuous phase of a colloid system; the medium in which a colloid is dispersed, corresponding to the solvent in a true solution.
enriched medium
modification of a basic medium for the growth of fastidious bacteria. Common additions are blood, serum or egg yolk.
indicator medium
a type of bacteriological medium which may contain a fermentable sugar plus a pH indicator that gives a color change. It is used to identify bacteria on the basis of a characteristic biochemical reaction.
refracting medium
the transparent tissues and fluid in the eye through which light rays pass and by which they are refracted and brought to a focus on the retina.
medium sausage
a technique for examining meat for bacterial contamination. The solid medium is made up in the form of a sausage and slices are removed from it after application of the exposed end to the suspect meat.
selective medium
formulated to facilitate the isolation of specific bacteria, they contain substances to inhibit growth of others.
transport medium
formulated to preserve a specimen, usually tissue or microbiological swab, and minimize bacterial overgrowth for the time necessary to transport it to the laboratory.