Starter

a culture containing yeast or bacteria that is used to start the process of fermentation or souring in making butter or cheese or dough

an electric motor for starting an engine

a hand tool consisting of a rotating shaft with parallel handle

the official who signals the beginning of a race or competition

any new participant in some activity

food or drink to stimulate the appetite (usually served before a meal or as the first course)

a contestant in a team sport who is in the game at the beginning