This might be just a supplemental entry adding to an entry in the Main Volume.
bæc-bord
;n. (not m.). Add :-- Hé lét him þá wídsǽ on ðæt bæc*-*bord, Ors. 1, 1; Swt. 17, 11, 27: 19, 17, 35, 30. On bæcbord him wæs Langaland, 35. [Icel. bak-borði, -borð larboard.]
Cite the scanned version of the original dicionary like this:
Toller, T. Northcote, and Joseph Bosworth. "bæc-bord." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth : Supplement. Oxford: Clarendon Press, 1921. 6.
, es; m. The larboard or left-hand side of a ship, when looking towards the prow or head; navigii sinistra pars :-- Burgenda land wæs us on bæcbord the land of the Burgundians was on our larboard or left, Ors. 1, 1; Bos. 21, 44. [Plat. Dut. bakboord the larboard.]