An essential element in the diet and a major component of bone.
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A nonmetallic chemical element, atomic no. 15, atomic wt. 30.973762, occurring extensively in nature always in combination as phosphates, phosphites, etc., and as the phosphate in every living cell; the elemental form is extremely poisonous, causing intense inflammation and fatty degeneration; repeated inhalation of p. fumes may cause necrosis of the jaw (phosphonecrosis); the approximate fatal dose is 50–100 mg. [G. phosphoros, fr. phos, light, + phoros, bearing]
- amorphous p., red p. an allotropic form of p. formed by heating ordinary p., in the absence of oxygen, to 260°C; it occurs as an amorphous dark red mass or powder, nonpoisonous, and much less flammable than ordinary p.; it may be reconverted to the latter by heating to 454.4°C in nitrogen gas.
- p. pentoxide the ultimate anhydride of orthophosphoric acid; a drying and dehydrating agent; corrosive.

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phos·pho·rus 'fäs-f(ə-)rəs n, often attrib a nonmetallic multivalent element that occurs widely in combined form esp. as inorganic phosphates in minerals, soils, natural waters, bones, and teeth and as organic phosphates in all living cells and that exists in several allotropic forms symbol P see ELEMENT (table)

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a nonmetallic element. Phosphorus compounds are major constituents in the tissues of both plants and animals. In humans, phosphorus is mostly concentrated in bone. However, certain phosphorus-containing compounds - for example adenosine triphosphate (ATP) and creatine phosphate - play an important part in energy conversions and storage in the body. In a pure state, phosphorus is toxic. Symbol: P.

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phos·pho·rus (P) (fosґfə-rəs) [Gr. phōs light + phorein to carry] a nonmetallic, allotropic element: poisonous and highly inflammable; atomic number, 15; atomic weight, 30.974. It occurs in three forms—white (yellow), red, and black. It is obtainable from bones, urine, and especially minerals, such as apatite. Phosphorus is an essential element in the diet; it is a major component of the mineral phase of bone and is abundant in all tissues, being involved in some form in almost all metabolic processes. Free phosphorus causes a fatty degeneration of the liver and other viscera, and the inhalation of its vapor often leads to necrosis of the lower jaw. It is used in homeopathic medicine.

Medical dictionary. 2011.

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