bougar

Borrowed from Scots bougar, from Middle Scots bougar, bouger, bowgar (“a cross-spar in a roof”), of obscure origin; perhaps representing Old English *bogagār (“arched beam”), from boga (“bow, arch”) + gār (“spear”), with the vocalism later being influenced by Middle Scots bow (“to bow, bend”). However, the supposed semantic development of gār is strained even with the parallels of Old English nafugār (“auger”) and Old Norse geirr (“point of an anvil”).

来源：wiktionary