Definitions of yell:

• noun:   a loud utterance of emotion (especially when inarticulate)

  Example: "A yell of pain"

• noun:   a loud utterance; often in protest or opposition
• verb:   utter or declare in a very loud voice

  Example: "You don't have to yell--I can hear you just fine"

• verb:   utter a sudden loud cry

  Example: "I yelled to her from the window but she couldn't hear me"

• name:  A surname (very rare: popularity rank in the U.S.: #26911)