The term 'MAD DOG' can be broken down into two crossword solutions: GROWLER (7 letters) and RABID (5 letters). GROWLER is a term used to describe a loud, deep-throated bark or howl, usually made by a large dog. RABID is an adjective used to describe someone or something that is extremely enthusiastic or passionate about something. Together, the two words form the phrase 'MAD DOG', which is often used to describe someone who is aggressive, violent, and out of control.