Beater - Protects other players from the Bludgers by hitting them away with a wooden club. See 'Quidditch'

Bertie Bott's Every-Flavour Beans - Popular jelly bean sweets in the wizarding world that come in every flavour imaginable. 

Bezoar - A stone taken from the stomach of a goat. It acts as an antidote to most poisons, but does not work for everything, such as Basilisk venom. Usually made of hair, plant fibre or similar indigestible objects.

Boil-Cure Potion - AKA Cure for Boils. A potion which cures boils, even those produced by the Pimple Jinx. The cauldron must be taken off the fire before adding the porcupine quills or the cauldron will melt and create a foul odour, and if it gets on the skin it will erupt in vicious boils. A successful potion will have pink smoke raising from the cauldron.

Bludger - Round, black ball made of iron. Bewitched to fly at the players and try to knock them off their brooms. The Beaters must protect the players from these balls. See 'Quidditch'

Broomstick - Device used for flying and to transport oneself between locations. The sport 'Quidditch' is played on brooms. Known broomstick models are Cleansweep One-Seven and Cleansweep Eleven, Nimbus 2000 and 2001, and the Firebolt.

Burn Hazel - See 'Nettle'