The Oxford Thesaurus An A-Z Dictionary of Synonyms - murderous adj.

1) fatal, lethal, deadly, deathly, mortal, destructive, devastating, sanguinary, bloody, brutal, savage, bloodthirsty, barbarous, fell, cruel, inhuman: The tolling of the bell signalled that the murderous deed had been done. 2) killing, strenuous, stressful, difficult, arduous, exhausting, hellish, harrowing, rigorous, intolerable, unbearable: You cannot keep up such a murderous pace, without any rest, and remain healthy.