Synonyms for Deathly (same or very similar meaning)
WordNet sense 1 (causing or capable of causing death):
deadly, mortalWordNet sense 2 (bringing death):
fatalWordNet sense 3 (having the physical appearance of death):
deathlikeWordNet sense 4 (no longer having or seeming to have or expecting to have life):
deadFrom the ODE community, based on WordNetadd/edit