taru-adjective, adverb taking the 'to' particle
magnificent; grand; imposing; grandly; boldly
Describes a dignified, majestic appearance or a confident, imposing manner. As a taru-adjective, it often modifies nouns (堂々たる態度). As an adverb with と, it describes acting in a grand or confident way.
彼の堂々たる態度に圧倒された。
I was overwhelmed by his dignified demeanor.
選手たちは堂々と入場行進した。
The athletes marched in grandly.
taru-adjective, adverb taking the 'to' particle
fair; open; unashamed; brazen; squarely
Used for behavior that is open, fair, or unashamed, sometimes with a nuance of brazenness. Often appears in contexts like 堂々と主張する (assert openly) or 堂々と振る舞う (act without shame).
彼は自分の意見を堂々と述べた。
He stated his opinion openly and confidently.
不正を堂々と行うなんて信じられない。
I can't believe they commit fraud so brazenly.