Source : Webster's Revised Unabridged Dictionary (1913)

Phosphorus \Phos"phor*us\, n.; pl. {Phosphori}. [L., the morning
   star, Gr. ?, lit., light bringer; ? light + ? to bring.]
   1. The morning star; Phosphor.

   2. (Chem.) A poisonous nonmetallic element of the nitrogen
      group, obtained as a white, or yellowish, translucent waxy
      substance, having a characteristic disagreeable smell. It
      is very active chemically, must be preserved under water,
      and unites with oxygen even at ordinary temperatures,
      giving a faint glow, -- whence its name. It always occurs
      compined, usually in phosphates, as in the mineral
      apatite, in bones, etc. It is used in the composition on
      the tips of friction matches, and for many other purposes.
      The molecule contains four atoms. Symbol P. Atomic weight
      31.0.

   3. (Chem.) Hence, any substance which shines in the dark like
      phosphorus, as certain phosphorescent bodies.

   {Bologna phosphorus} (Chem.), sulphide of barium, which
      shines in the dark after exposure to light; -- so called
      because this property was discovered by a resident of
      Bologna. The term is sometimes applied to other compounds
      having similar properties.

   {Metallic phosphorus} (Chem.), an allotropic modification of
      phosphorus, obtained as a gray metallic crystalline
      substance, having very inert chemical properties. It is
      obtained by heating ordinary phosphorus in a closed vessel
      at a high temperature.

   {Phosphorus disease} (Med.), a disease common among workers
      in phosphorus, giving rise to necrosis of the jawbone, and
      other symptoms.

   {Red, or Amorphous}, {phosphorus} (Chem.), an allotropic
      modification of phosphorus, obtained as a dark red powder
      by heating ordinary phosphorus in closed vessels. It is
      not poisonous, is not phosphorescent, and is only
      moderately active chemically. It is valuable as a chemical
      reagent, and is used in the composition of the friction
      surface on which safety matches are ignited.

   {Solar phosphori} (Chem.), phosphorescent substances which
      shine in the dark after exposure to the sunlight or other
      intense light.