Irreducible /(?)/

Ir·re·du·ci·ble

Irreducible

a.
  1. Incapable of being reduced, or brought into a different state; incapable of restoration to its proper or normal condition; as, an irreducible hernia.
  2. Incapable of being reduced to a simpler form of expression; as, an irreducible formula. (Math.)

Phrases & Compounds
Irreducible case
a particular case in the solution of a cubic equation, in which the formula commonly employed contains an imaginary quantity, and therefore fails in its application.