Webster's Dictionary, 1913

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Micro-geological adjective Of or pertaining to micro-geology.

Micro-geology noun [ Micro- + geology .] The part of geology relating to structure and organisms which require to be studied with a microscope.

Microcosmic, Microcosmical adjective [ Confer French microcosmique .] Of or pertaining to the microcosm.

Microcosmic salt (Chemistry) , a white crystalline substance obtained by mixing solutions of sodium phosphate and ammonium phosphate, and also called hydric-sodic- ammonic-phosphate . It is a powerful flux, and is used as a substitute for borax as a blowpipe reagent in testing for the metallic oxides. Originally obtained by the alchemists from human urine, and called sal microcosmicum .

Microcosmography noun [ Microcosm + -graphy .] Description of man as a microcosm.

Microcoulomb noun [ Micro- + coulomb .] (Electricity) A measure of electrical quantity; the millionth part of one coulomb.

Microcoustic adjective [ Micro- + acoustic : confer French microcoustique , micracoustique .] Pertaining, or suited, to the audition of small sounds; fitted to assist hearing.

Microcoustic noun An instrument for making faint sounds audible, as to a partially deaf person.

Microcrith noun [ Micro- + crith .] (Chemistry) The weight of the half hydrogen molecule, or of the hydrogen atom, taken as the standard in comparing the atomic weights of the elements; thus, an atom of oxygen weighs sixteen microcriths . See Crith . J. P. Cooke.

Microcrystalline adjective [ Micro- + crystalline .] (Crystallog.) Crystalline on a fine, or microscopic, scale; consisting of fine crystals; as, the ground mass of certain porphyrics is microcrystalline .

Microcyte noun [ Micro- + Greek ... a hollow vessel.] (Physiol.) One of the elementary granules found in blood. They are much smaller than an ordinary corpuscle, and are particularly noticeable in disease, as in anæmia.

Microdont adjective [ Micr- + Greek 'odoy`s , 'odo`ntos , a tooth.] (Anat.) Having small teeth.

Microfarad noun [ Micro- + farad .] (Electricity) The millionth part of a farad.

Microform noun [ Micro- + form , noun ] (Biol.) A microscopic form of life; an animal or vegetable organism of microscopic size.

Micrograph noun [ See Micrography .] An instrument for executing minute writing or engraving.

Micrographic adjective Of or pertaining to micrography.

Micrography noun [ Micro- + -graphy : confer French micrographie .] The description of microscopic objects.

Microhm noun [ Micr- + ohm .] (Electricity) The millionth part of an ohm.

Microlepidoptera noun plural [ New Latin See Micro- , and Lepidoptera .] (Zoology) A tribe of Lepidoptera, including a vast number of minute species, as the plume moth, clothes moth, etc.

Microlestes noun [ New Latin , from Greek mikro`s small + ... a robber.] (Paleon.) An extinct genus of small Triassic mammals, the oldest yet found in European strata.

Microlite noun [ Micro- + -lite .] (Min.)


1. A rare mineral of resinous luster and high specific gravity. It is a tantalate of calcium, and occurs in octahedral crystals usually very minute.

2. (Min.) A minute inclosed crystal, often observed when minerals or rocks are examined in thin sections under the microscope.

Microlith noun [ Micro- + lith .] (Min.) Same as Microlite , 2.

Microlithic adjective Formed of small stones.

Micrologic, Micrological adjective Of or pertaining to micrology; very minute; as, micrologic examination. -- Mi`cro*log"ic*al*ly , adverb

Micrology noun [ Micro- + -logy .]


1. That part of science which treats of microscopic objects, or depends on microscopic observation.

2. Attention to petty items or differences. W. Taylor.

Micromere noun [ Micro- + -mere .] (Biol.) One of the smaller cells, or blastomeres, resulting from the complete segmentation of a telolecithal ovum.

Micrometer noun [ Micro- + -meter : confer French micromètre .] An instrument, used with a telescope or microscope, for measuring minute distances, or the apparent diameters of objects which subtend minute angles. The measurement given directly is that of the image of the object formed at the focus of the object glass.

Circular, or Ring , micrometer , a metallic ring fixed in the focus of the object glass of a telescope, and used to determine differences of right ascension and declination between stars by observations of the times at which the stars cross the inner or outer periphery of the ring. -- Double image micrometer , a micrometer in which two images of an object are formed in the field, usually by the two halves of a bisected lens which are movable along their line of section by a screw, and distances are determined by the number of screw revolutions necessary to bring the points to be measured into optical coincidence. When the two images are formed by a bisected object glass, it is called a divided-object-glass micrometer , and when the instrument is large and equatorially mounted, it is known as a heliometer . -- Double refraction micrometer , a species of double image micrometer, in which the two images are formed by the double refraction of rock crystal. -- Filar, or Bifilar , micrometer . See under Bifilar . -- Micrometer caliper or gauge (Mech.) , a caliper or gauge with a micrometer screw, for measuring dimensions with great accuracy. -- Micrometer head , the head of a micrometer screw. -- Micrometer microscope , a compound microscope combined with a filar micrometer, used chiefly for reading and subdividing the divisions of large astronomical and geodetical instruments. -- Micrometer screw , a screw with a graduated head used in some forms of micrometers. -- Position micrometer . See under Position . -- Scale , or Linear , micrometer , a minute and very delicately graduated scale of equal parts used in the field of a telescope or microscope, for measuring distances by direct comparison.

Micrometric, Micrometrical adjective [ Confer French micrométrique .] Belonging to micrometry; made by the micrometer. -- Mi`cro*met"ric*al*ly , adverb

Micrometry noun The art of measuring with a micrometer.

Micromillimeter noun [ Micro- + millimeter .] The millionth part of a meter.

Micron noun [ New Latin , from Greek mikro`s small.] (Physics) A measure of length; the thousandth part of one millimeter; the millionth part of a meter.

Micronesian adjective [ From Micronesia , from Greek mikro`s small + nh^sos an island.] Of or pertaining to Micronesia, a collective designation of the islands in the western part of the Pacific Ocean, embracing the Marshall and Gilbert groups, the Ladrones, the Carolines, etc.

Micronesians noun plural ; sing. Micronesian . (Ethnol.) A dark race inhabiting the Micronesian Islands. They are supposed to be a mixed race, derived from Polynesians and Papuans.

Micronometer noun [ Micro- + chro nometer .] An instrument for noting minute portions of time.

Micropantograph noun [ Micro- + pantograph .] A kind of pantograph which produces copies microscopically minute.

Microparasite noun A parasitic microörganism. -- Mi`cro*par`a*sit"ic adjective

Micropegmatite noun [ Micro- + pegmatite .] (Min.) A rock showing under the microscope the structure of a graphic granite (pegmatite). -- Mi`cro*peg`ma*tit"ic adjective

Microphone noun [ Micro- + Greek ... sound, voice: confer French microphone .] (Physics) An instrument for intensifying and making audible very feeble sounds. It produces its effects by the changes of intensity in an electric current, occasioned by the variations in the contact resistance of conducting bodies, especially of imperfect conductors, under the action of acoustic vibrations.

Microphonic adjective Of or pert. to a microphone; serving to intensify weak sounds.

Microphonics noun [ See Microphone .] The science which treats of the means of increasing the intensity of low or weak sounds, or of the microphone.

Microphonous adjective Serving to augment the intensity of weak sounds; microcoustic.

Microphotograph noun [ Micro- + photograph .]


1. A microscopically small photograph of a picture, writing, printed page, etc.

2. An enlarged representation of a microscopic object, produced by throwing upon a sensitive plate the magnified image of an object formed by a microscope or other suitable combination of lenses.

» A picture of this kind is preferably called a photomicrograph .

Microphotography noun The art of making microphotographs.

Microphthalmia, Microphthalmy noun [ Micro- + Greek 'ofqalmo`s eye.] An unnatural smallness of the eyes, occurring as the result of disease or of imperfect development.

Microphyllous adjective [ Micro- + Greek fy`llon leaf.] (Botany) Small- leaved.

Microphytal adjective (Botany) Pertaining to, or of the nature of, microphytes.

Microphyte noun [ Micro- + Greek ... a plant: confer French microphyte .] (Botany) A very minute plant, one of certain unicellular algæ, such as the germs of various infectious diseases are believed to be.

Micropyle noun [ Micro- + Greek ... gate, orifice: confer French micropyle .] (Biol.) (a) An opening in the membranes surrounding the ovum, by which nutrition is assisted and the entrance of the spermatozoa permitted. (b) An opening in the outer coat of a seed, through which the fecundating pollen enters the ovule. -- Mi*crop"y*lar adjective

Microscopal adjective Pertaining to microscopy, or to the use of the microscope. Huxley.

Microörganism noun [ Micro- + organism .] (Biol.) Any microscopic form of life; -- particularly applied to bacteria and similar organisms, esp. such are supposed to cause infectious diseases.