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acute appalling awful baleful bitter burning calamitous clamant climactic critical crucial deplorable desperate destructive disastrous dolorous drastic dread dreadful extreme fearful formidable frightful/frightening gravest grim grave grievous harmful heartbreaking hellfire horrendous ill-boding inauspicious incommunicable indefinable inexpressible insistent instant lamentable minatory more acute more climacteric more climactic more crucial more critical more desperate more frightening more horrendous more painful more pressing more terrible mortal most awful most climacteric most crucial most climactic most frightening most horrendous most pressing most terrible nagging nightmarish ominous painful pressing regrettable requiring ruinous sinister smarting somber terrible threatening tragic tumbledown undescribable unlucky unspeakable unutterable