/ ˈbuːstə(r); NAmE / noun
1.
(also ˈbooster rocket ) a rocket that gives a spacecraft extra power when it leaves the earth, or that makes a missile go further
2.
a device that gives extra power to a piece of electrical equipment
3.
an extra small amount of a drug that is given to increase the effect of one given earlier, for example to protect you from a disease for longer :
a tetanus booster
4.
a thing that helps, encourages or improves sb/sth :
a morale / confidence booster
5.
( especially NAmE ) a person who gives their support to sb/sth, especially in politics :
a meeting of Republican boosters