\Po"rism\, n. [Gr. ? a thing procured, a deduction from a
demonstration, fr. ? to bring, provide: cf. F. porisme.]
1. (Geom.) A proposition affirming the possibility of finding
   such conditions as will render a certain determinate
   problem indeterminate or capable of innumerable solutions.
   --Playfair.
2. (Gr. Geom.) A corollary. --Brande & C.
Note: Three books of porisms of Euclid have been lost, but
      several attempts to determine the nature of these
      propositions and to restore them have been made by
      modern geometers.