Japanese has several words for safety and stability, each differing in meaning and nuance.
大丈夫 (All right)
大丈夫 is a broad word for saying that something is fine or not a problem. Context determines the meaning, so 大丈夫 covers more ground than the other words in this group.
Takeo takes his pregnant mother to the hospital, as she’s getting close to delivery. Once there, she gives Takeo and his friend Suna a list of things to take care of during her stay.
安心( describes freedom from anxiety. It names the calm one feels when they believe things are secure. Since that feeling depends on the individual’s experience and circumstances, one person can feel 安心( in a situation that still worries someone else.
In this scene, Nishikata faces no danger. He feels anxious because he thinks he has forgotten an important date.
平気 (Composed)
平気( describes someone who stays unaffected or unbothered by something that might cause worry. It describes whether a situation has danger. 平気( focuses on the person’s reaction, so someone can be 平気( even in an uncomfortable situation.
無事( describes coming through something without injury or trouble. It is used after danger or uncertainty has passed to confirm that nothing bad happened.
After school, Ninako notices Ren sleeping a few seats away on the train. When Ren wakes and rushes for his stop, he knocks Ninako’s phone from her hand. The phone hits the floor, and the strap charm breaks. Ren misses his exit while apologizing and offers to replace the charm.
安全( describes a situation with no danger, independent of how anyone feels about it. It points to external conditions, such as a safe method or a safe place.
Coco and her friends are trapped in a maze and trying to find a way past a dragon. Seeing the others working out magic to use, Coco tries her hand at a spell, creating a flame. Agott isn’t impressed, but Tetia feels otherwise.
テティア:
「炎(が安定(してる!」
“The flame is stable!”
「前(はすぐ落(ちて燃(え尽(きちゃってたのにいつの間(に!?」
“It used to go out and burn out right away, so when did this happen!?”