Calm and composed; unperturbed and self-possessed in any situation.
面接のときでも彼女は泰然自若として、落ち着いて話していた。
Even during the interview she was calm and composed, speaking steadily.
緊急事態にもかかわらず、隊長は泰然自若な態度で指示を出した。
Despite the emergency, the captain gave orders with a composed demeanor.
泰然自若は敬意を表す表現だが、日常会話ではやや硬く聞こえる。
泰然自若 expresses respectfulness, but it sounds somewhat formal in everyday conversation.