| pervaporation | The heating of a liquid within a dialyzing bag suspended over a hot plate, evaporation taking place rapidly through the membrane; any colloids in solution remain within the bag while crystalloids diffuse out and crystallise on the outer surface of the bag (perstillation). Origin: L. Per, through, + vapor, steam (05 Mar 2000) |
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| pervasive development disorder | <neurology, psychiatry> A large group of developmental disabilities which are neurological disorders, usually of unknown cause. Characteristics include reduced abilities to understand language and communicate normally, reduced ability to socially interact with others in a normal manner, and limited variety in activities and interests. Individuals will also often respond in unusual ways to sensations, engage in repetitive activities, and resist changes to the environment or to daily routines. Types of pervasive development disorder include autism, Retts Syndrome, Hellers Syndrome, and Aspergers Syndrome. Acronym: PDD (12 Jan 1998) |
| pervasive developmental disorder | A class of mental disorders of infancy, childhood, or adolescence characterised by distortions in the development of the multiple basic psychological functions involved in the development of social skills and language. (05 Mar 2000) |
| pervenous pacemaker | An artificial pacemaker passed through the venous circulation into the right side of the heart. (05 Mar 2000) |
| perversion | <psychology> A turning aside from the normal course, a morbid alteration of function which may occur in emotional, intellectual or volitional fields. In psychiatry, sexual deviation. Origin: L. Versio = a turning (18 Nov 1997) |
| pervert | One who practices perversions. See: deviant. (05 Mar 2000) |
| perverted | Abnormal, deviant, or disordered. (05 Mar 2000) |
| pervigilium | Wakefulness; sleeplessness. Origin: L. A watching all night (05 Mar 2000) |
| pervious | 1. Admitting passage; capable of being penetrated by another body or substance; permeable; as, a pervious soil. "[Doors] . . . Pervious to winds, and open every way." (Pope) 2. Capable of being penetrated, or seen through, by physical or mental vision. "God, whose secrets are pervious to no eye." (Jer. Taylor) 3. Capable of penetrating or pervading. 4. <ornithology, zoology> Open; used synonymously with perforate, as applied to the nostrils or birds. Origin: L. Pervis; per + via a way. See Per-, and Voyage. Source: Websters Dictionary (01 Mar 1998) |