1. One that boosts, as:
a. A device for increasing power or effectiveness.
b. An enthusiastic promoter, as of a sports team or school.
c. Electronics A radio-frequency amplifier.
d. The primary stage of a multistage rocket that provides the main thrust for launch, liftoff, and initial flight.
2. A booster shot.
3. Slang One who steals goods on display in a store.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.