1911 Encyclopædia Britannica/Trilemma
TRILEMMA (Gr. τρεῖς, three, λῆμμα, something taken), in logic, an argument akin to the dilemma (q.v.), in which there are three possibilities. By getting rid of two, the third is proved, provided the original three exhaust the number. The terms “tetralemma” (four possibilities) and “polylemma” (many) have also been used.