n
1 thing that boosts 令人鼓舞的事物
*a morale booster, ie sth that makes one feel more confident 精神鼓舞.
2 device for increasing power or voltage 增强动力或电压的装置.
3 (also `booster rocket) rocket used to give initial speed to a missile or spacecraft 助推火箭（给予导弹或航天器以初速度的）.
4 dose or injection (of a medicine or drug) that increases the effect of an earlier one 辅助药剂, 增效药剂（用以加强前次药剂效力的）.

n[C]
a small quantity of a drug that increases the effect of one that was given before, so that someone continues to be protected against a disease
　a booster shot
something that helps someone or something to increase or improve, or to be more successful or confident
　a booster pump
　a profit booster for the company
morale/confidence booster
　Mail from home is a big morale booster for far-away troops.
a rocket that is used to provide extra power for a spacecraft to leave the Earth
　a giant booster rocket
AmE someone who gives a lot of support to a person, organization, or an idea
　a dance organized by the school's booster club