An underground shelter or tunnel built for protection against enemy air raids.

(idiom) utterly lacking in substance or meaning; describes speech or writing that is empty, shallow, and has no real content

completely empty or bare; wide and vacant (used for physical spaces like rooms or caves)

empty; deserted; describing a state of being spacious and void of people or things

a region of marked thinning of the ozone layer in high latitudes, allowing harmful ultraviolet radiation to reach the surface of the earth

a region of marked thinning of the ozone layer in high latitudes, especially over the Antarctic