n.
Function: noun
Etymology: Dutch, tree, beam; akin to Old High German boum tree ― more at BEAM
Date: 1627
1 : a long spar used to extend the foot of a sail
2 a : a chain or line of connected floating timbers extended across a river, lake, or harbor (as to obstruct passage or catch floating objects) b : a temporary floating barrier used to contain an oil spill
3 a : a long beam projecting from the mast of a derrick to support or guide cargo b : a long more or less horizontal supporting arm or brace (as for holding a microphone or for supporting an antenna)
4 : a spar or outrigger connecting the tail surfaces and the main supporting structure of an aircraft