adverb taking the 'to' particle, taru-adjective
blushing; flushing red
Rare literary term describing a person turning red in the face, typically from embarrassment or shame. Used with と or in たる adjective constructions.
He blushed and looked down.
He apologized with a flushed face.
From Chinese 赧然 (nǎnrán), meaning 'blushing'. The kanji 赧 means 'blush' or 'be ashamed', and 然 is a suffix forming adjectives/adverbs. The exact historical derivation into Japanese is uncertain, but it is a literary borrowing.