| deradelphus | Conjoined twins with a single head and neck and separate bodies below the thoracic level. See: conjoined twins. Origin: G. Dere, neck, + adelphos, brother (05 Mar 2000) |
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| derailment | A symptom of a thought disorder in which one constantly gets "off the track" in his thoughts and speech; similar to loosening of association. (05 Mar 2000) |
| deranencephaly | 1. Congenital malformation in which the head is absent, although there is a rudimentary neck. 2. Defect of the brain and upper part of the spinal cord. Origin: G. Dere, neck, + an-, priv., + kephale, head (05 Mar 2000) |
| derange | 1. To put out of place, order, or rank; to disturb the proper arrangement or order of; to throw into disorder, confusion, or embarrassment; to disorder; to disarrange; as, to derange the plans of a commander, or the affairs of a nation. 2. To disturb in action or function, as a part or organ, or the whole of a machine or organism. "A sudden fall deranges some of our internal parts." (Blair) 3. To disturb in the orderly or normal action of the intellect; to render insane. Synonym: To disorder, disarrange, displace, unsettle, disturb, confuse, discompose, ruffle, disconcert. Origin: F. Deranger; pref. De- = des- (L. Dis) + ranger to range. See Range, and cf. Disarrange, Disrank. Source: Websters Dictionary (01 Mar 1998) |
| derangement | 1. A disturbance of the regular order or arrangement. 2. Rarely used term for a mental disturbance or disorder. Origin: Fr. Hey's internal derangement, dislocation of the semilunar cartilages of the knee joint. (05 Mar 2000) |
| derbio | <zoology> A large European food fish (Lichia glauca). Source: Websters Dictionary (01 Mar 1998) |
| derby hat fracture | Regular cranial concavity in infants; may or may not be associated with fracture Synonym: dishpan fracture. (05 Mar 2000) |
| derbyshire spar | <chemical> A massive variety of fluor spar, found in Derbyshire, England, and wrought into vases and other ornamental work. Source: Websters Dictionary (01 Mar 1998) |
| Dercum's disease | <disease> A disease accompanied by painful localised fatty swellings and by various nerve lesions. It is usually seen in women and may cause death from pulmonary complications. (12 Dec 1998) |
| Dercum, Francis | <person> U.S. Neurologist, 1856-1931. See: Dercum's disease. (05 Mar 2000) |
| derealization | An alteration in one's perception of the environment such that things that are ordinarily familiar seem strange, unreal, or two-dimensional. (05 Mar 2000) |
| dereism | Mental activity in fantasy in contrast to reality. Origin: L. De, away, + res, thing (05 Mar 2000) |
| dereistic | Living in imagination or fantasy with thoughts that are incongruent with logic or experience. (05 Mar 2000) |
| derencephalia | Cervical rachischisis and anencephaly, a malformation involving an open cranial vault with a rudimentary brain usually crowded back toward bifid cervical vertebrae. Synonym: derencephalia. Origin: G. Dere, neck, + enkephalos, brain (05 Mar 2000) |
| derencephalocele | In derencephaly, protrusion of the rudimentary brain through a defect in the upper cervical spinal canal. Origin: G. Dere, neck, + enkephalos, brain, + kele, hernia (05 Mar 2000) |
| van der Hoeve's syndrome | <syndrome> A subtype of osteogenesis imperfecta in which progressive conductive hearing loss begins in childhood because of stapedial fixation. (05 Mar 2000) |
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| van der Kolk, Jacobus | <person> Dutch physician, 1797-1862. See: van der Kolk's law. (05 Mar 2000) |
| van der Kolk's law | In a mixed nerve, the sensory fibres are distributed to the parts moved by the muscles controlled by the motor fibres. (05 Mar 2000) |
| van der Velden, Reinhardt | <person> German physician, 1851-1903. See: van der Velden's test. (05 Mar 2000) |
| van der Velden's test | A test for free hydrochloric acid, the presence of which turns an added solution of methylene blue from violet to green. (05 Mar 2000) |
| van der Waals attraction | <chemistry> Electrodynamic forces arise between atoms, molecules and assemblies of molecules due to their vibrations giving rise to electromagnetic interactions, these are attractive when the vibrational frequencies and absorptions are identical or similar, repulsive when nonidentical. Other interactions originally proposed by van der Waals were included in this name, but these are usually separated into the Coulomb's force, the Keesom force and the London force. Only the last is of electrodynamic nature. Probably important in holding lipid membranes into that structure and possibly in other interactions, for example cell adhesion. Electrodynamic forces between large scale assemblies can be of relatively long range nature. (18 Nov 1997) |
| van der Waals' forces | First postulated by van der Waals in 1873 to explain deviations from ideal gas behaviour seen in real gases; the attractive force's between atoms or molecules other than electrostatic (ionic), covalent (sharing of electrons), or hydrogen bonding (sharing a proton); generally ascribed to dipolar and dispersion effects, π-electrons, etc.; these relatively nondescript force's contribute to the mutual attraction of organic molecules. Synonym: London forces. (05 Mar 2000) |
| van der Waals, Johannes | <person> Dutch physicist and Nobel laureate, 1837-1923. See: van der Waals' forces. (05 Mar 2000) |