opaqu- +

A metallic salt often found in association with binding proteins; such as, antibodies: "An electron-opaque tracer is used to detect the presence of specific molecules or structures in an electron microscopic examination of a sample."

A medical contrast medium, or contrast agent, that is a trademark which is used for the preparation of a diagnostic radiopaque medium: "An Isopaque is a substance used to enhance the variations of structures or fluids within the body during medical X-ray imaging."

"The Isopaque is commonly used to show the differences between the visibility of blood vessels and the gastrointestinal tract in the body."

1. Physically allowing the passage of radiation, or X-rays, to go through objects: "The nonopaque radiation procedures make it possible for X-rays to be radiolucent or to allow the passage of radiant energy to go through materials because they are not blocking the the process."
2. Not being difficult to understand; and so, being clear and obvious: "The nonopaque language of the scientist made it possible for the non-scientific audience to understand what he was talking about."

1. A thick or dark condition that makes something; such as, glass or a liquid difficult to see through: "The opacity of the windows were a result of not having the accumulation of dirt cleaned off."

"Opacities represent the degrees to which light is obscured by pollutant particles in the air."

2. Having difficulty in understanding statements, presentations, or in explaining something: "Students had difficulty in understanding the opacity of the scientific presentation."

"The opacities of most dictionaries simply don't give people clear or straightforward definitions."

3. Etymology: "darkness, obscurity", from French opacité; from Latin opacitatem, opacitas, "shade, shadiness"; from opacus, "shaded, dark".

A medium that does not pass radiation of a particular frequency band: "Opaque projectors are used to view images of nontransparent materials; such as, printed sheets, pages of books, or drawings onto a screen by means of reflected light."

1. Not clear; not transmitting radiant energy, sound, heat, etc.: "Opaque elements are characterized by being opposite to that of transparency; for example, steel is an opaque material that blocks visible light."

"Certain chemical solutions are opaque to ultraviolet radiations."

"There was a dust cloud of opaque pollution over the city that was caused by the dust storm."

2. Not clearly understood or expressed; not clear or lucid; obscure: "Medical dictionaries too often provide the most opaque definitions of any of the lexicons."

"Despite the professor's help, the problem still seems opaque to the student."

3. Impervious to light; not translucent or only slightly so: "The opaque glass blocked any possibility of looking outside the windows."
4. Not allowing light to pass through: "The opaque water of the muddy river made it impossible to see anything below the surface of the water."
5. Not shining, without luster, not reflecting light; or being dark or dull: "The opaque paint on the car would not reflect the glare from the sun even on very sunny days."
6. Dull, stupid, or unintelligent: "Some of the most opaque remarks are presented by certain radio talk-show hosts."

"It's amazing how some politicians can pass such opaque bills that waste so much federal money."

7. Etymology: from opake which came from Latin opacus, "dark, shaded, shady" of uncertain origin. The current English spelling of opaque was influenced from about 1650 by French opaque which came from Latin.

Unable to see through something or not transparent: "The opaquely steamed windows prevented anyone from being able to see through them."

1. The quality or the degree to which something reduces the passage of light: "The opaqueness of the dirty windows permitted little light to pass through them and so they were not translucent or they were clear enough for light to pass through but not only with difficulty."

"Dust storms are common across Arizona during dry and windy conditions, and walls of dust more than a mile high can blanket an area in a matter of seconds, sometimes reducing visibility to zero or complete opaqueness."

2. Incomprehensibility resulting from the obscurity or difficulty of understanding someone or something: "The opaqueness of technical jargon found in most scientific dictionaries makes it very difficult for the average user to understand what is being presented."

"Why do so many medical lexicons have such opaqueness in their content?"

A substance; for example, metal, will be highlighted (appear white) on a plain X-ray: "The use of iodine containing radiopaque contrast dyes allow enhancement of the anatomy to be demonstrable with a conventional X-ray."

Not permitting the passage of x-rays: "Roentgenopaque or radiopaque x-rays are impenetrable to certain materials and so an image is produced on a radiosensitive surface; such as, photographic film, by radiation other than with visible light."

"There are roentgenopaque materials that are not penetrable by roentgen rays at the commonly used diagnostic energy ranges. Such roentgenopaque areas appear light or white on exposed films."

Partially, nearly, or half transmitting or reflecting light or radiant energy: "Many of the new buildings in the city have semiopaque windows."

"Some semiopaque glazes are applied to ceramics before firing so they will have a smooth lustrous surface and be more attractive."