fateful (Adjective) — Having momentous consequences; of decisive importance. ex. "that fateful meeting of the U.N. when...it declared war on North Korea"
fateful (Adjective) — Ominously prophetic.
fateful (Adjective) — (of events) having extremely unfortunate or dire consequences; bringing ruin. ex. "a fateful error"
fateful (Adjective) — Controlled or decreed by fate; predetermined. ex. "a fateful series of events"