Boreout syndrome is a contemporary work-life problem that emerges when an employee experiences underchallenge, disinterest, and boredom in the workplace in a prolonged and intense manner. Although the concept of burnout has been extensively studied in the academic literature for many years, boreout syndrome stands out as a relatively new area of research. The aim of this chapter is to comprehensively examine the conceptual foundations, historical development, core components, antecedents, symptoms, and consequences of boreout syndrome, as well as to evaluate the concept within the context of Industry 4.0 and Industry 5.0. In this regard, Rothlin and Werder's original boreout approach, Schaufeli and Salanova's work psychology perspective, Stock's empirical measurement model, and recent international research are jointly addressed. The chapter explains the three core components of boreout syndrome -underchallenge, disinterest, and boredom- and discusses its relationship with concepts such as burnout, quiet quitting, presenteeism, and inner resignation. Furthermore, antecedents such as job design, organizational practices, overqualification, and person-job misfit are evaluated, along with the psychological, behavioral, and organizational consequences of the syndrome. Literature findings indicate that boreout syndrome creates significant adverse effects on employees' psychological well-being, job performance, innovative work behavior, and organizational commitment. It is assessed that digitalization and automation in the Industry 4.0 process may increase the risk of boreout, whereas the human-centric approach of Industry 5.0 holds the potential to mitigate this risk through meaningful job design, job crafting, and employee well-being-oriented practices. In conclusion, it is emphasized that boreout syndrome is not merely an individual problem but a significant work psychology issue with organizational and structural dimensions.