booster
noun
[ ˈbuːstə ]
• a device for increasing electrical voltage or signal strength.
• the first stage of a rocket or spacecraft, used to give initial acceleration and then jettisoned.
• a dose of a vaccine that increases or renews the effect of an earlier one.
• "boosters at five-year intervals are recommended"
• a source of help or encouragement.
• "job fairs are a great morale booster"
• a shoplifter.
