Booster

A booster may mean:

a booster dose in medicine, refers to a vaccination given after a previous vaccination. A booster helps maintain or increase a protective immune response.
a booster pack is a pack of 8-19 cards in a trading card game.
a person who promotes his or her town or region – see boosterism
a booster rocket used in space flight to provide the main thrust in the initial phase of the rocket's flight
a co-channel repeater in broadcasting, used to improve signal strength
a booster seat, used by children after outgrowing a highchair
a booster shot – a follow-up to a vaccine
a booster engine - extra cylinders on a steam locomotive, driving the trailing truck or a tender truck, to give more power on starting
a booster draft - a way to play a collectible card game with a limited pool of cards.
a booster unit - a cabless diesel locomotive used to boost the power of a locomotive consist but incapable of being used on its own. See B unit.
an explosive booster - a bridge between a low energy explosive and a low sensitivity explosive.
Booster is also the name of a strange clown-like character who has his own amusement tower in the videogame Super Mario RPG.