Definitions of starter:

• noun:   an electric motor for starting an engine
• noun:   the official who signals the beginning of a race or competition
• noun:   a contestant who is in the game at the beginning
• noun:   a culture containing yeast or bacteria that is used to start the process of fermentation or souring in making butter or cheese or dough

  Example: "To make sourdough you need a starter"

• noun:   a hand tool consisting of a rotating shaft with parallel handle
• noun:   food or drink to stimulate the appetite (usually served before a meal or as the first course)
• noun:   any new participant in some activity