terribilis (causing fright; terrificus is poetical only): horribilis: horrendus (causing horrour): atrox (fearful, frightful; e.g., death, bloodshed): immanis (monstrous, quite unnatural, cruel; e.g., animal, deed, character): foedus (causing indignation, abominable; e.g., projects, war, fire, or conflagration): dirus (dire): trux (causing men to shudder; e.g., of looks): incredibilis (that can’t be conceived, e.g., stupidity, stupiditas): to be the bearer of some dreadful news, miros terrores afferre ad aliquem.