Source : Webster's Revised Unabridged Dictionary (1913)

Discus \Dis"cus\, n.; pl. E. {Discuses}, L. {Disci}. [L. See
   {Disk}.]
   1.
      (a) A quoit; a circular plate of some heavy material
          intended to be pitched or hurled as a trial of
          strength and skill.
      (b) The exercise with the discus.

   Note: This among the Greeks was one of the chief gymnastic
         exercises and was included in the Pentathlon (the
         contest of the five exercises). The chief contest was
         that of throwing the discus to the greatest possible
         distance.

   2. A disk. See {Disk}.

Source : WordNet®

disci
     See {discus}

discus
     n 1: an athletic competition in which a disc-shaped object is
          thrown as far as possible
     2: a disk used in throwing competitions [syn: {saucer}]
     [also: {disci} (pl)]