| dark lantern |
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noun
- A lantern with a panel that slides to block the light.
- 1891, w:Arthur_Conan_Doyle, Sir Arthur Conan Doyle, w:The_Red-Headed_League, The Red-Headed League:
- :In the meantime Mr. Merryweather, we must put the screen over that ."
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| definition |
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noun
- A statement of the meaning of a word or word group or a sign or symbol (dictionary definitions).
- A statement expressing the essential nature of something.
- The action or process of defining.
- The act of defining; determination of the limits.
- A product of defining.
- The action or power of describing, explaining, or making definite and clear.
- Her comic genius is beyond .
- Clarity of visual presentation, distinctness of outline or detail.
- The of a telescope.
- Improve the of an image.
- Clarity, especially of musical sound in reproduction.
- Sharp demarcation of outlines or limits.
- A jacket with distinct waist .
- (bodybuilding) The degree to which individual muscles are distinct on the body.
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| deflection |
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noun
- The act of deflecting or something deflected.
- The deviation of a needle or other indicator from its previous position.
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| density |
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noun (pl=densities)
- A measure of the amount of matter contained by a given volume.
- The ratio of the number particles or total amount of such a quantity as energy or momentum, carried by or contained in a volume , to that volume.
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| dextrorotatory |
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adjective (symbol d-)
- (chemistry) of an optically active compound or crystal that rotates the plane of polarized light to the right, or clockwise
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| diaphragm |
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noun
- (anatomy) In mammals, a sheet of muscle separating the thorax from the abdomen, contracted and relaxed in respiration to draw air into and expel air from the lungs.
- (mechanics) A flexible membrane separating two chambers and fixed around its periphery that distends into one or other chamber depending on the as the difference in the pressure in the chambers varies.
- A contraceptive device consisting of a flexible cup, used to cover the cervix during intercourse.
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| diffuse |
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verb (diffus, ing)
- (transitive) To spread over or through as in air, water, or other matter, especially by fluid motion or passive means.
- (intransitive) To be spread over or through as in air, water, or other matter, especially by fluid motion or passive means.
- Food coloring diffuses in water.
- The riot diffused quite suddenly.
adjective
- Everywhere or throughout everything; not focused or concentrated.
- Such a effort is unlikely to produce good results.
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| diopter |
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noun
- A unit of measure of the power of a lens or mirror, equal to the reciprocal of its focal length in meters. Myopia is diagnosed and measured in diopters.
- (obsolete) Any lens system, such as a telescope
- (obsolete) A theodolite or similar surveyor's angle measuring device
- (obsolete) An alhidade
- (obsolete) A surgical speculum
- (obsolete) An instrument for drawing the skull by projections.
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| dioptric |
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noun
- (in plural) The branch of optics concerned with refraction.
- A dioptric telescope.
adjective
- (obsolete) Pertaining to a diopter.
- Acting as a medium for sight; making use of refraction (of lenses, etc.).
- (obsolete) Capable of being seen through.
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| dioptrics |
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noun
- plural of dioptric
- the study of the refraction of light, especially by lenses
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| disperse |
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verb (disperses, dispersing, dispersed)
- To scatter abroad so as to drive to different parts; to distribute; to diffuse; to spread; to scatter, so as to cause to vanish; to dissipate; as, to disperse vapors.
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| distortion |
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noun (wikipedia, distortion, distortion (physics))
- An act of distorting.
- A result of distorting.
- A misrepresentation of the truth.
- The story he told was a bit of a .
- noise, Noise or other artifacts caused in the electronic reproduction of sound or music.
- This recording sounds awful due to the .
- An effect used in music, most commonly on guitars in rock or metal.
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| doublet |
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noun
- a man"s close-fitting jacket, with or without sleeves. Men in Europe wore doublets from the 1400s to the 1600s.
- a pair of two similar or equal things; couple.
- one of two or more different words in a language derived from the same origin but coming by different routes.
- An imitation gem made of two pieces of glass or crystal with a layer of color between them.
- (printing, US) A word or phrase set a second time by mistake.
- (quantum mechanics) A quantum state of a system with a spin of 1/2, such that there are two allowed values of the spin component, -1/2 and +1/2.
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