na-adjective, noun
stout-hearted; firm; courageous
Describes a person who remains mentally strong and unshaken in adversity; often used for someone who does not show weakness or despair despite difficult circumstances.
彼女は気丈にも、涙を見せずに話し続けた。
She stout-heartedly continued speaking without showing tears.
気丈に振る舞おうと
I tried to act firm, but my voice trembled.
Compound of 気 (spirit, mind) and 丈 (length, stature), suggesting a 'tall spirit' or strong-mindedness. The exact historical derivation is uncertain, but the kanji combination conventionally conveys mental fortitude.