| volatilise | To cause or undergo evaporation. Synonym: volatilise. (05 Mar 2000) |
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| volatilization | Synonym: evaporation. Origin: fr. L. Volatilis, volatile, fr. Volo, pp. Volatus, to fly (05 Mar 2000) |
| volator | <zoology> Same as Volador. Source: Websters Dictionary (01 Mar 1998) |
| volcanic | 1. Of or pertaining to a volcano or volcanoes; as, volcanic heat. 2. Produced by a volcano, or, more generally, by igneous agencies; as, volcanic tufa. 3. Changed or affected by the heat of a volcano. Volcanic bomb, a mass ejected from a volcano, often of molten lava having a rounded form. Volcanic cone, a hill, conical in form, built up of cinders, tufa, or lava, during volcanic eruptions. Volcanic foci, the subterranean centers of volcanic action; the points beneath volcanoes where the causes producing volcanic phenomena are most active. Volcanic glass, the vitreous form of lava, produced by sudden cooling; obsidian. See Obsidian. Volcanic mud, fetid, sulphurous mud discharged by a volcano. Volcanic rocks, rocks which have been produced from the discharges of volcanic matter, as the various kinds of basalt, trachyte, scoria, obsidian, etc, whether compact, scoriaceous, or vitreous. Origin: Cf. F. Volcanique, It. Vulcanico. Source: Websters Dictionary (01 Mar 1998) |
| volcanic eruption | The ash, dust, gases, and lava released by volcanic explosion. The gases are volatile matter composed principally of about 90% water vapor, and carbon dioxide, sulfur dioxide, hydrogen, carbon monoxide, and nitrogen. The ash or dust is pyroclastic ejecta and lava is molten extrusive material consisting mainly of magnesium silicate. (12 Dec 1998) |
| volcano | Origin: It. Volcano, vulcano, fr. L. Vulcanus Vulkan, the god of fire. See Vulkan. <geology> A mountain or hill, usually more or less conical in form, from which lava, cinders, steam, sulphur gases, and the like, are ejected; often popularly called a burning mountain. Volcanoes include many of the most conspicuous and lofty mountains of the earth, as Mt. Vesuvius in Italy (4,000 ft. High), Mt. Loa in Hawaii (14,000 ft), Cotopaxi in South America (nearly 20,000 ft), which are examples of active volcanoes. The crater of a volcano is usually a pit-shaped cavity, often of great size. The summit crater of Mt. Loa has a maximum length of 13,000 ft, and a depth of nearly 800 feet. Beside the chief crater, a volcano may have a number of subordinate craters. Source: Websters Dictionary (01 Mar 1998) |
| vole | <zoology> Any one of numerous species of micelike rodents belonging to Arvicola and allied genera of the subfamily Arvicolinae. They have a thick head, short ears, and a short hairy tail. The water vole, or water rat, of Europe (Arvicola amphibius) is a common large aquatic species. The short-tailed field vole (A. Agrestis) of Northern and Central Europe, and Asia, the Southern field vole (A. Arvalis), and the Siberian root vole (A. Oeconomus), are important European species. The common species of the Eastern United States (A. Riparius) (called also meadow mouse) and the prairie mouse (A. Austerus) are abundant, and often injurious to vegetation. Other species are found in Canada. Source: Websters Dictionary (01 Mar 1998) |
| vole bacillus | An acid-fast bacillus isolated from voles and used in the production of a vaccine against human and bovine tuberculosis. (05 Mar 2000) |
| Volhard's test | A test for renal function: the patient drinks 1500 ml of water on an empty stomach; if the patient was not dehydrated beforehand and the kidneys are normal, this fluid will be excreted by the end of 4 hr, with specific gravity of the urine being from 1.001 to 1.004. (05 Mar 2000) |
| Volhard, Franz | <person> German physician, 1872-1950. See: Volhard's test. (05 Mar 2000) |
| volition | Voluntary activity without external compulsion. (12 Dec 1998) |
| volitional | Done by an act of will; relating to volition. (05 Mar 2000) |
| volitional tremor | A tremor that can be arrested by a strong effort of the will. Synonym: intention tremor. (05 Mar 2000) |
| Volkmann's canals | Vascular canal's in compact bone that, unlike those of the haversian system, are not surrounded by concentric lamellae of bone; they run for the most part transversely, perforating the lamellae of the haversian system, and communicate with the canal's of that system. (05 Mar 2000) |
| Volkmann's cheilitis | An acquired disorder, of unknown aetiology, of the lower lip characterised by swelling, ulceration, crusting, mucous gland hyperplasia, abscesses, and sinus tracts. Synonym: Baelz' disease, myxadenitis labialis, Volkmann's cheilitis. (05 Mar 2000) |