taru-adjective, adverb taking the 'to' particle
peaceful and lovely; humble and dignified
Archaic literary term describing a serene, graceful, and dignified atmosphere or demeanor. Used in classical Chinese-influenced Japanese writing.
古い漢詩に「穆穆たる春の光」という表現が見られる。
In old Chinese-style poetry, one finds the expression 'peaceful and lovely spring light'.