starter

noun

1. an electric motor for starting an engine
2. a contestant in a team sport who is in the game at the beginning
3. the official who signals the beginning of a race or competition
4. any new participant in some activity
5. food or drink to stimulate the appetite (usually served before a meal or as the first course)
6. a hand tool consisting of a rotating shaft with parallel handle
7. a culture containing yeast or bacteria that is used to start the process of fermentation or souring in making butter or cheese or dough"to make sourdough you need a starter"