hermetic
adjective uk/hɜːˈmet.ɪk/ us/hɚˈmet̬.ɪk/
engineering specialized（容器）密封的，不透气的
(of a container) so tightly closed that no air can leave or enter
a hermetic seal 密封垫
formal（人群）与世隔绝的，不与外界往来的
If a particular group is hermetic, the people who live within it don't often communicate with those who live outside it.
He entered the hermetic world of the monastery at a young age. 他很年轻时就进了与世隔绝的修道院。