Definition of Prognostic

Prognostic: 1. (adjective) In medicine, relating to the prognosis of a disease. For example, a favorable prognostic factor.
2. (adjective) Generally, relating to a prediction. For example, a prognostic index for the economy.
3. (noun) In medicine, an indicator of the course of a disease.
4. (noun) Any type of prediction.

The word prognostic is far more often used today as an adjective than as a noun. Prognostic is taken from the Greek prognostikos (of knowledge beforehand). It combines pro (before) and gnosis (a knowing). Hippocrates used the word prognosis, much as we do today, to mean a foretelling of the course of a disease.