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.

&fist; 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.