Definitions of bellow:

• noun:   a very loud utterance (like the sound of an animal)

  Example: "His bellow filled the hallway"

• noun:   United States novelist (born in Canada in 1915)
• verb:   make a loud noise, as of animal

  Example: "The bull bellowed"

• verb:   shout loudly and without restraint
• name:  A surname (very rare: popularity rank in the U.S.: #28002)