Baith, both.
Barmy-brained, giddy, feather-brained.
Baron-bailie, a kind of magistrate, the baron's deputy in a burgh of barony.
Basket-beagles, beagles that chased a hare slipped from a basket.
Bauld, bold.
Bawbee, a halfpenny.
Bedral, a sexton.
Begum, an Indian princess, or lady of high rank.
Bidden, remained.
Blawort, a bluebottle.