bonspiel - a curling tournament. See long post by Sparteye - Hog on Ice

borax
n.
5ME < ML borax < Ar bauraq < Pers bdrah6
1 sodium borate, a white, anhydrous, crystalline salt, Na2B4O7, with an alkaline taste, used as a flux in soldering metals and in the manufacture of glass, enamel, artificial gems, soaps, antiseptics, etc.
>2 5from the furniture formerly given as premiums by manufacturers of borax soap6 cheap, poorly made merchandise, esp. furniture

bordeereau - French = memorandum (and bank statements, etc.)

botryoidal - like a bunch of grapes. synonym, aciniform. "Racemus" is Latin, but "racemose"
is not a synonym, strangely.

boresight If you mount a telescopic sight on a rifle, it is helpful if rifle is type that has
a removable bolt which enables you to look through the barrel at a target, with rifle held
in vise on bench. Then the scope can be adjusted to point at same target. Then the
rifle can be fired, and impact point used to correct the scope.

boubou - used several different ways in French. One of most common is elaborate colorful
dress of S.African society women.
But in US, most commonly refers to crack cocaine.

boutade - an outburst, especially of angry temper.