As you might guess, "fatidic" is a relative of the word fate. The Latin word for fate is "fatum," which literally means "what has been spoken." "Fatum," in turn, comes from fari, meaning "to speak." In the eyes of the ancients, your fate was out of your hands - what happened was up to gods and demigods. Predicting your fate was a job for oracles and prophets. "Fatidic" is "fatum" combined with dicere, meaning "to say." That makes "fatidic" a relative of the word predict as well; the "-dict" of "predict" also comes from Latin dicere.