This chapter clarifies what contemporary writers and laypeople mean by happiness. It distinguishes neighboring constructs—emotion, affect, mood, state, and trait—and maps time horizons from momentary feelings to life-as-a-whole judgments. The chapter synthesizes major typologies (pleasure-focused, life-evaluation, virtue-centered, and hybrids) and shows how different definitions yield different claims. It also reports recurrent patterns from cross-cultural and linguistic studies (e.g., work in Norway, Nigeria, India, Spain, Germany/South Africa, and analyses of Oromo usage), illustrating how folk concepts vary—emphasizing autonomy, social harmony, needs fulfillment, or everyday positive tone—while still sharing family resemblances. Ongoing debates are summarized, including whether to combine affect with life evaluation and whether moral virtue is required for happiness. The chapter closes with a practical clarity guide: specify what happiness denotes in context, the time frame and level of analysis, and the kinds of evidence you will rely on. The aim is a plural, clearly specified usage that respects cultural variation and supports cumulative scholarship and practice.