| geometric isomer | <chemistry> Geometric or also called cis-trans isomers are stereoisomers in molecules with restricted rotation about a bond. Cycloalkanes and alkenes form cis-trans isomers due to the restriction of rotation about the double bond or due to the restriction in a ring. In order for an alkene to freely rotate, the pi bond must be broken. This process has a high activation energy and does not occur at room temperature. Cis isomers have the two substituents on each of the carbons of the double bond on the same side, whereas in the trans isomer they are on opposite sides. The expression cis and trans only applies to alkenes or cycloalkanes if one of the substituents on each of the carbons are the same. If there are three or four different substituents, E,Z or R,S nomenclature must be used. (09 Jan 1998) |
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| geometric isomerism | A form of isomerism displayed by unsaturated or ring compounds where free rotation about a bond (usually a carbon-carbon bond) is restricted; e.g., the isomerism of a cis-or trans-compound as in oleic acid and elaidic acid. Compare: cis-, entgegen, trans-, zusammen. (05 Mar 2000) |
| geometric mean | The mean calculated as the antilogarithm of the arithmetic mean of the logarithms of the individual values; it can also be calculated as the nth root of the product of n values. (05 Mar 2000) |
| geometric mean diameter | A measure of the central tendency of particle size composition of substrate materials sometimes used as an index of the quality of spawning gravels. Also referred to as D50 size. (09 Oct 1997) |
| atrophic glossitis | An erythematous, edematous, and painful tongue which appears smooth due to loss of the filiform and sometimes the fungiform papillae secondary to certain nutritional deficiencies, especially B-vitamin deficencies, as seen in pellagra, thiamin deficiency, and disorders such as pernicious anaemia (Hunter's or Moeller's glossitis). Synonym: bald tongue. (05 Mar 2000) |
| benign migratory glossitis | <clinical sign> A benign condition where there is a map-like appearance to the tongue resulting from irregular denuded patches in the surface (loss of tongue papillae). Likely secondary to local irritation from hot or spicy foods, alcohol or tobacco. There are no significant complications. (27 Sep 1997) |
| glossitis | <pathology> Inflammation of the tongue. (14 Oct 1997) |
| glossitis areata exfoliativa | <clinical sign> A benign condition where there is a map-like appearance to the tongue resulting from irregular denuded patches in the surface (loss of tongue papillae). Likely secondary to local irritation from hot or spicy foods, alcohol or tobacco. There are no significant complications. (27 Sep 1997) |
| glossitis, benign migratory | An inflammatory disease of the tongue of unknown aetiology, characterised by multiple annular areas of desquamation of the filiform papillae on the dorsal surface of the tongue, usually presenting pinkish-red central lesions outlined by thin, yellowish lines or bands that change patterns and shift from one area to another every few days. (12 Dec 1998) |
| glossitis desiccans | A painful affection of the tongue, of unknown origin, in which the surface becomes raw and fissured. (05 Mar 2000) |
| Moeller's glossitis | An erythematous, edematous, and painful tongue which appears smooth due to loss of the filiform and sometimes the fungiform papillae secondary to certain nutritional deficiencies, especially B-vitamin deficencies, as seen in pellagra, thiamin deficiency, and disorders such as pernicious anaemia (Hunter's or Moeller's glossitis). Synonym: bald tongue. (05 Mar 2000) |
| Hunter's glossitis | See: atrophic glossitis. Median rhomboid glossitis, an asymptomatic, ovoid or rhomboid, macular or mamellated, erythematous lesion with papillary atrophy on the dorsum of the tongue just anterior to the circumvalate papillae; thought to represent a persistent tuberculum impar. (05 Mar 2000) |
| recurrent herpetic stomatitis | Reactivation of herpes simplex virus infection, characterised by vesicles and ulceration limited to the hard palate and attached gingiva. (05 Mar 2000) |
| primary herpetic stomatitis | First infection of oral tissues with herpes simplex virus; characterised by gingival inflammation, vesicles, and ulcers. (05 Mar 2000) |
| herpetic | 1. Relating to or characterised by herpes. 2. Relating to or caused by a herpetovirus or herpesvirus. (05 Mar 2000) |