adverb, adverb taking the 'to' particle, taru-adjective
Describes acting in a scared, hesitant, or overly cautious manner. Often used with する or と.
彼は恐々と部屋に入った。
He entered the room fearfully.
恐々しながら結果を待った。
I waited nervously for the result.
Reduplication of 恐 (きょう, 'fear'), forming an adverb expressing a fearful state. The exact historical derivation is uncertain.