| periodic neutropenia | Neutropenia recurring at regular intervals (14 to 45 days), in association with various types of infectious diseases, e.g., stomatitis, cutaneous ulcers, furuncles, arthritis, and others. Synonym: cyclic neutropenia. (05 Mar 2000) |
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| periodic oedema | A vascular reaction involving the deep dermis or subcutaneous or submucal tissues, representing localised oedema caused by dilatation and increased permeability of the capillaries and characterised by development of giant wheals. (18 Nov 1997) |
| periodic ophthalmia | An acute iridocyclitis of horses, involving one or both eyes; it subsides only to recur at intervals of varying length and usually ends in blindness; the cause is uncertain but some have associated it with leptospires; does not appear to be contagious. Synonym: moon blindness. (05 Mar 2000) |
| periodic paralysis | Term for a group of diseases characterised by recurring episodes of muscular weakness or flaccid paralysis without loss of consciousness, speech, or sensation; attacks begin when the patient is at rest, and there is apparent good health between attacks. See: hyperkalaemic periodic paralysis, hypokalaemic periodic paralysis, normokalaemic periodic paralysis. (05 Mar 2000) |
| periodic peritonitis | familial paroxysmal polyserositis |
| periodic polyserositis | familial paroxysmal polyserositis |
| periodic system | The arrangement of the chemical elements in a definite order as indicated by their respective atomic numbers in such a way that groups of elements with similar chemical properties (similar valence shell electron number) are grouped together. See: Mendeleeff's law. (05 Mar 2000) |
| periodical | 1. Of or pertaining to a period or periods, or to division by periods. "The periodicaltimes of all the satellites." (Sir J. Herschel) 2. Performed in a period, or regular revolution; proceeding in a series of successive circuits; as, the periodical motion of the planets round the sun. 3. Happening, by revolution, at a stated time; returning regularly, after a certain period of time; acting, happening, or appearing, at fixed intervals; recurring; as, periodical epidemics. "The periodic return of a plant's flowering." (Henslow) "To influence opinion through the periodical press." (Courthope) 4. Of or pertaining to a period; constituting a complete sentence. Periodic comet, the generalisation that the properties of the chemical elements are periodic functions of their atomic wieghts. "In other words, if the elements are grouped in the order of their atomic weights, it will be found that nearly the same properties recur periodically throughout the entire series." The arrangement of the atomic weights shows the regular recurrence of groups, each consisting of members of the same natural family. A similar relation had been enunciated in a crude way by Newlands; but the law in its effective form was developed and elaborated by Mendelejeff, whence it is sometimes called Mendelejeff's law. Important extensions of it were also made by L. Meyer. By this means Mendelejeff predicted with remarkable accuracy the hypothetical elements ekaboron, ekaluminium, and ekasilicon, afterwards discovered and named respectively scandium, gallium, and germanium. <astronomy> Periodic star, the time of a complete revolution of the body about the sun, or of a satellite about its primary. Origin: L. Periodicus, Gr., cf. F. Periodique. Source: Websters Dictionary (01 Mar 1998) |
| periodical index | Useful as a subject approach to the contents of a periodical issuing an annual, biennial, quinquennial, decennial, etc., index. The heading is used for the overall body of articles published by a periodical in the same sense that bibliography is useful when published as a single article. (12 Dec 1998) |
| periodicals | A publication issued at stated, more or less regular, intervals. (12 Dec 1998) |
| periodicity | The quality or state of being periodical, or regularly recurrent; as, the periodicity in the vital phenomena of plants. Origin: Cf. F. Periodicite. Source: Websters Dictionary (01 Mar 1998) |
| periodontal | <dentistry> Pertaining to your gums. For example periodontal disease is gum disease. (08 Jan 1998) |
| periodontal abscess | Localised circumscribed purulent area of inflammation in the periodontal tissue. It is a derivative of marginal periodontitis and commonly associated with suprabony and infrabony pockets and interradicular involvements, in contrast to periapical abscess which is attributable to pulp necrosis. (12 Dec 1998) |
| periodontal anaesthesia | Anaesthesia of the periodontal ligament, produced by injection of a local anaesthetic drug. (05 Mar 2000) |
| periodontal atrophy | Decrease in size and/or cellular elements of the periodontium after it has reached normal maturity. (05 Mar 2000) |