astrologer vs prognosticator

astrologer and prognosticator both are nouns.

Word	Noun	Adjective	Verb	Adverb
astrologer	Yes	No	No	No
prognosticator	Yes	No	No	No

As nouns, prognosticator is a hypernym of astrologer; that is, prognosticator is a word with a broader meaning than astrologer:

astrologer: someone who predicts the future by the positions of the planets and sun and Moon
prognosticator: someone who makes predictions of the future (usually on the basis of special knowledge)

Other hypernyms of astrologer include forecaster, predictor, soothsayer.

astrologer (noun)	prognosticator (noun)
someone who predicts the future by the positions of the planets and sun and Moon	someone who makes predictions of the future (usually on the basis of special knowledge)