Which term describes a predictive sign or omen?

The term "prognostic" refers specifically to something that serves as a sign or indication of a future event, often relating to predictions in contexts like health or weather. In the context of omens, a prognostic can be seen as a foretelling of what might happen, drawing from evidence or signs observed. This aligns perfectly with the concept of predictive signs, as it conveys the idea of something that signals a potential outcome based on existing conditions or phenomena.

The other terms do not fit this definition. "Aesthetic" relates to beauty or artistic principles rather than any predictive quality. "Abrogate" means to repeal or do away with a law or formal agreement and has no predictive connotation. "Aberration" refers to a deviation from what is typical or expected, which may imply something unusual but does not specifically denote a predictive sign or omen.