A bunker is a defensive military fortification designed to protect people and valuable materials from falling bombs, artillery, or other attacks. Bunkers are almost always underground, in contrast to blockhouses which are mostly above ground. There are different types of bunkers, including trench bunkers, which are small concrete structures partly dug into the ground, and industrial bunkers, which can be used for mining sites, food storage areas, dumps for materials, data storage, and sometimes living quarters. When a house is purpose-built with a bunker, the normal location is a reinforced below-ground bathroom with fiber-reinforced plastic shells.
In addition to its military use, the term "bunker" can also refer to a container for coal or other fuel. In golf, a bunker is a sand trap or embankment constituting a hazard on a golf course. The verb "to bunker" can mean to fill a ships bunker with coal or oil, to place or store something in a bunker, or to hit a golf ball or shot into a bunker.
