Green’s Dictionary of Slang

(Ulster) a bonfire, esp. one lit on 12 July, Orangeman’s Day.

1995		Sun. Trib. (Dublin) 9 July n.p.: We always had guards stationed in the boney to make sure no Taig, or even no Prod from any of the neighbouring streets, tried to set fire to it before the Eleventh [BS].
1996		(con. 1950s) C. Kenneally Maura’s Boy 75: We lit a ‘bona’.