Prognostic, n.
Etymology: [L. prognosticum, Gr. pronostic, prognostic. See Prognostic, a.]
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. That choice would inevitably be considered by the country as a prognostic of the highest import. Macaulay.
2. (Med.)
A sign or symptom indicating the course and termination of a disease. Parr.
Syn. -- Sign; omen; presage; token; indication.
2 other Webster entries under this spelling
Prognostic, a.
Indicating something future by signs or symptoms; foreshowing; aiding in prognosis; as, the prognostic symptoms of a disease; prognostic signs.
Prognostic, v. t.
To prognosticate. [Obs.]
Shades of meaning
Fernald has no entry of its own for prognostic; he lists it under sign.
He lists it without comment; the entries above explain its neighbors.