1. An underground shelter; especially, one that is built for troops, with a fortified gun position above ground: Naturally, after the war, many bunkers were abandoned by the troops.
2. A sand-filled hollow on a golf course, built as a hazard: The golf champ hit his ball into the bunker and had difficulty getting it out.
3. A fuel-storage container on a ship: The bunker was filled with 25,000 liters of gelled fuel for the sea voyage.
4. A large outdoor bin or chest: Farmer Joe kept his summer picnic equipment in a bunker out by the barn.
5. Etymology: from Scottish, "seat, bench", possibly a variant of banker, "bench" (1677).