The Collaborative International Dictionary
Precessional \Pre*ces"sion*al\, a. Of or pertaining to pression; as, the precessional movement of the equinoxes.
Wiktionary
a. Of or pertaining to precession
Usage examples of "precessional".
This tradition, as we saw in Part V, contained values for the rate of precessional motion that were so accurate and so consistent it was extremely difficult to attribute them to chance.
Nevertheless I could hardly forget that out of this very same Heliopolitan tradition the great myth of Isis and Osiris had flowed, covertly transmitting an accurate calculus for the rate of precessional motion.
By mimicking the sky pattern of Orion’s belt in 10,500 bc the three great Pyramids of Giza mark a very significant moment in the 20,000-year precessional cycle of these stars—the lowest point in their slide up and down the meridian, when (as seen from the latitude of Giza) they culminated at an altitude of 9 degrees 20 minutes above the horizon (C).
Nutation, or nodding, is a small but irregular movement that swings the celestial pole 10 seconds away from the smooth precessional circle every 18.