Definition of "bulldog" []

• Any of a breed of short-haired dog characterized by a large head, strong square jaws with dewlaps, and a stocky body. It was originally bred for bullbaiting. (noun)
• A short-barreled, large-caliber revolver or pistol. (noun)
• A heat-resistant material used to line puddling furnaces. (noun)
• Chiefly British A proctor's assistant at Oxford University or Cambridge University. (noun)
• Stubborn. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "I could now thoroughly appreciate the term bulldog, which I had heard applied to him by the soldiers."
• "You see, among his friends, Rubén was known as a bulldog because once he grabbed onto something, he never let go."
• "You see, among his friends, Rubén was known as a bulldog because once he grabbed onto something, he never let go."