booster
/ˈbuːstə(r)/noun
1
- a thing or person that helps increase or promote something, in particular起推动（或推进）作用的事（或人）, 尤指：
1.1
- Medicine a dose of an immunizing agent increasing renewing the effect of an earlier one【医】增强辅剂量。
1.2
- the first stage of a rocket or spacecraft, used to give initial acceleration and then jettisoned（火箭, 飞船的）助推器。
1.3
- a device for increasing electrical voltage or signal strength（电压的）增压器; （电信号的）放大器。
1.4
- in combination a source of help or encouragement推动; 鼓励：
job fairs are a great morale booster.
人才交流市场大大地鼓舞了人心。
1.5
- N. Amer. a keen promoter of a person, organization, or cause〈北美〉积极的支持者; 热心的拥护者。
2
- N. Amer. informal a shoplifter〈北美, 非正式〉（商店的）窃贼, 扒手。