barn door
noun
1
the fly on a pair of trousers. Used in the euphemistic warning: 'Your barn door is open' US, 1950.
2
any target that is too large to miss UK, 1679.
3
an extremely large halibut. Alaskan and Canadian usage CANADA, 1989.
4
in stage lighting, and the television and film industries, blinders used to focus a studio lamp. Conventionally known as a 'variable mask' US, 1960.
5
a type of fuel injection system US, 1965