na-adjective
profoundly quiet; serene; deeply tranquil
Literary and somewhat elevated; describes a place or atmosphere that is deeply quiet and peaceful, often with a sense of refined seclusion.
山奥の寺は幽静な雰囲気に包まれていた。
The temple deep in the mountains was enveloped in a profoundly quiet atmosphere.
彼は都会を離れ、幽静な土地で暮らしたいと思っている。
He wants to leave the city and live in a serene, secluded place.