R / rădĭātĭo
noun

rădĭātĭo

gen. rădĭātōnis · gender feminine · decl. 3rd
a glittering; shining; a beamy lustre
a glittering, shining, a beamy lustre, radiation (postAug.): marmoris, Plin. 36, 5, 4, § 32: stellarum, Jul. Firm. Math. 1, 4. — Plur., Arn. 6, 208.