having momentous consequences; of decisive importance; "that fateful meeting of the U.N. when...it declared war on North Korea"- Saturday Rev; "the fatal day of the election finally arrived"
inspiring fear; "the formidable prospect of major surgery"; "a tougher and more redoubtable adversary than the heel-clicking, jackbooted fanatic"- G.H.Johnston; "something unnerving and prisonlike about high grey wall"
extremely impressive in strength or excellence; "a formidable opponent"; "the challenge was formidable"; "had a formidable array of compositions to his credit"; "the formidable army of brains at the Prime Minister's disposal"
being or characterized by concepts or their formation; "conceptual discussions"; "the schizophrenic loses ability to abstract or do conceptual thinking"; "sex is a notional category, gender is a grammatical category"
shockingly repellent; inspiring horror; "ghastly wounds"; "the grim aftermath of the bombing"; "the grim task of burying the victims"; "a grisly murder"; "gruesome evidence of human sacrifice"; "macabre tales of war and plague in the Middle ages"; "macabre tortures conceived by madmen"
the calculated use of violence (or threat of violence) against civilians in order to attain goals that are political or religious or ideological in nature; this is done through intimidation or coercion or instilling fear