definition of bull slang
bull (plural bulls) 1  An adult male of domesticated cattle or oxen. 2  A male of domesticated cattle or oxen of any age. 3  An adult male of certain large mammals, such as whales, elephants and seals.  A large, strong 1  man. (finance) An investor who buys (commodities or securities) in anticipation of a rise in prices. ( slang) A policeman.