Booster doses have become a commonly used term nowadays amid the global COVID-19 pandemic. Although the term booster dose is now widely known, there are other synonyms that can be used to describe the same phenomenon. These include "third dose," "refresher shot," "reinforcement shot," or simply "booster shot." The term booster dose refers to an additional vaccine dose given to an individual several months after the initial vaccine doses. By doing so, it aims to boost immunity and provide better protection against the virus. As more and more countries introduce booster dose programs, it is essential to be familiar with other phrases that describe the same concept.