an increase in power, value, or effectiveness

• help or encouragement that improves results

a push from behind or below to help someone up

to increase or improve something

• to add power or effectiveness

to lift or push someone upward

• to help someone climb

to jump-start a vehicle with another vehicle’s battery

• to provide external battery power to start an engine

to steal, especially by shoplifting (informal)

a coordinate transformation that changes velocity in special relativity

intake manifold pressure above atmospheric in turbocharged engines

to give a booster vaccination

• to administer a booster dose

to amplify a signal or message

• to share widely online to increase reach