This chapter explores the evolving vocabulary of longevity by distinguishing three key spheres: the scientific field, the business industry, and the global movement. It examines how terminology shapes our understanding in longevity science, merges biotechnology, healthcare innovation, and consumer wellness in the longevity economy, and blends personal health advocacy with broader societal goals in the movement. By analyzing the most commonly used terms in each sphere, I also trace four referential periods that reflect the evolution of the longevity language. This chapter emphasizes the need for clarity in communication—critical in a multidisciplinary, high-stakes domain like longevity—where unambiguous language encourages alignment, reduces confusion, and bridges diverse fields of expertise.