adverb taking the 'to' particle, taru-adjective
boldly; resolutely; fearlessly
Describes taking action with firm determination and courage, often in the face of difficulty or opposition. Used adverbially with と, or attributively as a たる adjective in formal writing.
He resolutely confronted the difficulty.
He boldly stood up and exposed the wrongdoing.
困難に直面しても、敢然たる態度を崩さなかった。
Even when facing difficulties, he maintained a resolute attitude.
Everyone was moved by his resolutely bold attitude.
勇敢 is a general adjective/noun describing bravery as a trait, whereas 敢然 describes the bold manner of a specific action, often in formal writing.
大胆 focuses on boldness or audacity in general behavior, while 敢然 specifically conveys resolute courage in the face of difficulty.
敢えて shares the kanji 敢 with 敢然 but means 'daringly/deliberately doing something despite risk,' not 'boldly/resolutely' as a manner adverb.
Formed from the kanji 敢 (daring, bold) and the suffix 然 (indicating a state or manner). The exact historical derivation is uncertain, but it follows a classical Chinese pattern for forming adverbs/adjectives.