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"
easily spread; "fear is exceedingly infectious; children catch it from their elders"- Bertrand Russell
caused by infection or capable of causing infection; "viruses and other infective agents"; "a carrier remains infective without himself showing signs of the disease"
of or relating to infection; "infectious hospital"; "infectious disease"