Definition of "bull" []

• An adult male bovine mammal. (noun)
• The uncastrated adult male of domestic cattle. (noun)
• The male of certain other large animals, such as the alligator, elephant, or moose. (noun)
• An exceptionally large, strong, and aggressive person. (noun)
• An optimist, especially regarding business conditions. (noun)

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.

• "This plastic resin bull is the size of a red blood cell."
• "The name bull trout has a long history, especially in Idaho and Montana, and is the common name chosen by Cavender."
• "But all these, down to the fifteenth century, seem to have been expedited by the papal chancery in the shape of bulls authenticated with leaden seals, and it is common enough to apply the term bull even to those very early papal letters of which we know little more than the substance, independently of the forms under which they were issued."