calm, cool, and collected; composed; unruffled
A yojijukugo describing a person who remains calm and level-headed even under pressure. Often used to praise composure in difficult situations.
He remained calm and collected even in the emergency.
She approached the negotiation with a composed attitude.
冷静 is a common word for 'calm' or 'cool-headed'. 沈着冷静 is a more emphatic, four-character compound that adds the nuance of being unshaken and collected.
落ち着いている is a more everyday expression for being calm and settled. 沈着冷静 is more formal and often used in written or rhetorical contexts.
A yojijukugo combining 沈着 (composure, calmness) and 冷静 (cool-headedness). The exact historical derivation is uncertain, but it follows a common pattern of pairing synonymous two-character compounds for emphasis.