Definitions of tag:

• noun:   (sports) the act of touching a player in a game (which changes their status in the game)
• noun:   a game in which one child chases the others; the one who is caught becomes the next chaser
• noun:   a label made of cardboard or plastic or metal
• noun:   a small piece of cloth or paper
• verb:   provide with a name or nickname
• verb:   attach a tag or label to
• verb:   touch a player while he is holding the ball
• verb:   supply (blank verse or prose) with rhymes
• verb:   go after with the intent to catch
• name:  A surname (very rare: popularity rank in the U.S.: #77374)