prognostic(n = noun.event) omen, portent, presage, prodigy, prognostication - a sign of something about to happen; "he looked for an omen before going into battle"
is a kind of augury, foretoken, preindication, sign
has particulars: auspice, foreboding, death knell
Derived form adjective prognostic₁

   prognostic(s = adj.all) predictive, prognosticative - of or relating to prediction; having value for making predictions;
Derived forms noun prognosis₂, noun prognosis₁, noun prognostic₁

   Indicating something future by signs or symptoms; foreshowing; aiding in prognosis; as, the prognostic symptoms of a disease; prognostic signs. [1913 Webster]

1.  That which prognosticates; a sign by which a future event may be known or foretold; an indication; a sign or omen; hence, a foretelling; a prediction. [1913 Webster]
"That choice would inevitably be considered by the country
as a prognostic of the highest import." [1913 Webster]

2.  A sign or symptom indicating the course and termination of a disease. Parr. [1913 Webster]

   To prognosticate. [1913 Webster]

prognostic, n. & adj.
--n.
1 (often foll. by of) an advance indication or omen, esp. of the course of a disease etc.
2 a prediction; a forecast.
--adj. foretelling; predictive (prognostic of a good result).

Derivative:
prognostically adv.

Etymology:
ME f. OF pronostique f. L prognosticum f. Gk prognostikon neut. of prognostikos (as PROGNOSIS)

N  omen, portent, presage, prognostic, augury, auspice, sign, harbinger, yule candle, bird of ill omen, signs of the times, gathering clouds, warning, prefigurement, ill-boding, auspicium melioris aevi.