安堵

The word "安堵" describes a specific emotional transition: the feeling of relief that occurs precisely when a source of anxiety, tension, or fear is removed. While it is similar to "安心 (anshin)," "安堵" is significantly more formal and is predominantly used in written Japanese or formal speech.

In contrast, "安心" is a broader term that can describe a general state of peace or security (e.g., "a safe neighborhood" or "feeling secure in a relationship"), whereas "安堵" almost always implies a preceding state of worry. You would rarely use "安堵" in a casual conversation with friends; instead, you would use "安心した."

Commonly, it appears in the set phrase "安堵の息をつく" (to breathe a sigh of relief), which vividly captures the physical release of tension after a period of stress.