Complete composure; showing no sign of agitation or perturbation. A yojijukugo often used in written or formal contexts.
彼は試験中も神色自若で、周りの騒ぎに一切動じなかった。
He remained perfectly composed during the exam and didn't react to the commotion around him.
交渉の場であの外交官はいつも神色自若の態度を崩さない。
That diplomat never loses his composure at negotiation tables.
記者の問いに対しても、彼女は神色自若に答え続けた。
Even when questioned by reporters, she continued to answer calmly and collectedly.