More than two decades after his seminal paper 'Subjective Well-Being', Ed Diener wrote that he substituted happiness with well-being to obtain scientific credibility. Are the arguments echoed in positive psychology rigorous enough to justify this substitution? This article focuses on the historical examination of the word happiness, covering the lexical universes of ancient Greek, Latin, and English, seeking to identify the connections between them. We found that arguments for such substitution are sustained by a fragile appreciation of the semantic depth of happiness. Although it favors quantification, the current understanding of well-being obliterates the plurality of the debate about happiness and the recognition of other ideals of life. Thus, we conclude that well-being and happiness are semantically close, but conceptually, metaphysically, and empirically distinct, demanding, as objects, particular investigations.