'Fēng shān' literally means 'to seal the mountain' — 'fēng' (封) means 'to seal, close off, or prohibit access to', and 'shān' (山) means 'mountain'. Together, the term describes an official action where authorities temporarily or permanently restrict public entry into a mountain area. This is commonly done for ecological protection, wildlife conservation (e.g., to shield endangered species’ habitats), fire prevention during dry seasons, or recovery after natural disasters like landslides.

The phrase carries a formal, administrative tone and appears frequently in government notices, environmental reports, and news headlines. It implies top-down regulation rather than informal closure; you wouldn’t use it for a personal hiking trail you decide not to visit. While 'fēng' alone can mean 'to seal' in many contexts (e.g., sealing a letter), 'fēng shān' is a fixed compound used exclusively for mountains under official management.