The phrase "ill omened" means something that is considered a bad or unlucky sign. Its antonym would be "auspicious", meaning something that is considered to be lucky or a good sign. Another antonym for "ill omened" would be "propitious", which means favorable or giving signs of success. Some other antonyms for "ill omened" include "fortunate", "prosperous", "promising", and "hopeful." It is important to note that these antonyms are not interchangeable, but they each represent a different aspect of a positive omen or sign. Ultimately, the opposite of "ill omened" is something that gives hope, positivity, and good fortune.