Thesauruses and dictionaries do not seem to mention what the antonym of an omen is, but they do mention that and omen is a "sign of something to come." So, if an omen means to predict something that has not happened yet, then the opposite of an omen would either be to predict what has happened long ago or something that has already happened.
There are many synonyms listed for the word portent. However, there is only one listed antonym for this word and it is doom.
prophecy, warning, prognostic, premonition, indication, augury, foreboding, harbinger
unknown
omen
The word omen is an abstract noun.
synonymize
"Alternate word" is a noun-phrase that is kind of a synonym for the word "synonym. There is no one exact word that means the same as synonym.
The antonym of the word 'synonym' is 'antonym'.
indication, sign, portent, forerunner
Conjecture, omen, prophecy, augury...
omen
alerts, warns, admonition, counsels, forewarning, hints, omen, sign, tip-off
The word omen is not a bad word
Omen
The word omen is an abstract noun.
That was not a good omen.
Omen = 'ōuli
Sure, a synonym for "auspices" could be "patronage" or "support."
omen means in portuguese: presságio, agouro
EX.. my dogs is a omen dogs