プログレッシブ和英中辞典(第4版)の解説
れいせい【冷静】
冷静な（に） calm(ly)
冷静になる
calm down
間もなく彼は冷静さを取り戻した
Soon he regained his composure [self-possession].
彼女は努めて冷静を装った
She tried hard to look calm [composed/self-possessed].
彼は常に冷静だ
He always 「keeps his presence of mind [maintains his composure/《口》 keeps his cool].
危機に当たって冷静を保つのは重要だ
It's important to keep your head in a crisis.
あの人はすぐに冷静さを失う
He is easily upset.／He often loses 「his head [his presence of mind/his composure].
冷静な態度で
calmly／in a calm manner
冷静な判断力
the ability to judge coolly [calmly]