noun

• Initialism of Burger King: a fast-food restaurant chain.
• Abbreviation of book. [A collection of sheets of paper bound together to hinge at one edge, containing printed or written material, pictures, etc.]
• Abbreviation of black. [(countable and uncountable) The colour/color perceived in the absence of light, but also when no light is reflected, but rather absorbed.]
• (video games, slang) Initialism of bad kid, an inexperienced player or noob.