This is the 2448th most frequent Japanese word.
不可欠
Indispensable; essential.
Here, '不可欠' conveys the idea of being crucial and indispensable.
技術革新は現代社会の発展に不可欠です。
Technological innovation is essential for the development of modern society.
In this sentence, '不可欠' describes health as a necessary and foundational aspect.
健康は幸福な生活を送るために不可欠な要素です。
Health is an essential element for leading a happy life.
This use of '不可欠' highlights an imperative quality required for achievement.