R / rētrōgrădātĭo
noun

rētrōgrădātĭo

gen. rē^trōgrădātōnis · gender feminine · decl. 3rd
retrogradior
a going back; retrograding
a going back, retrograding (late Lat.), Mart. Cap. 8, § 881: stellarum, Isid. Orig. 3, p. 83.