<p>Studies investigating well-being dimensions and interventions to promote it primarily rely on data collection through scaled questionnaires. Based on a qualitative, bottom-up approach, this study was aimed at exploring how teachers working at different school levels define happiness in their own words. To this purpose, 504 Brazilian teachers aged 20–65 completed the Eudaimonic and Hedonic Happiness Inventory (EHHI), a mixed-method instrument including, among others, an open-ended question inviting participants to provide their own definition of happiness. The sample was divided into five professional groups (kindergarten, elementary, middle and high school, academic staff, and principals). The definitions of happiness were coded and analyzed, considering the participants’ sociodemographic features. Answers were categorized into psychological and contextual definitions, equally represented in percentage. Among psychological definitions, inner harmony ranked first, followed by satisfaction. Contextual definitions primarily referred to relationships with family and significant others. Differences emerged in the percentage of participants quoting categories and subcategories across professional and demographic features, with significantly more younger teachers defining happiness as satisfaction and achievement and older ones working as principals quoting harmony. Proposals to promote teachers’ well-being should consider shared dimensions, such as the pursuit of harmonious relationships in the work context, and specific aspects, such as opportunities for professional growth and rewards for younger professionals.</p>