booster

noun

1. 1

   an additional dose that makes sure the first dose was effective

2. 2

   the first stage of a multistage rocket

3. 3

   an amplifier for restoring the strength of a transmitted signal

4. 4

   a thief who steals goods that are in a store

5. 5

   someone who is an active supporter and advocate

6. 6

   a person who backs a politician or a team etc.

   all their supporters came out for the game

   they are friends of the library