Background <p>Palliative care nurses, who are consistently exposed to patients in the advanced stages of life-threatening illnesses, are at heightened risk of experiencing emotional distress and compassion fatigue, which can compromise the quality of care and patient satisfaction. This study aimed to explore the perceptions of palliative care nurses regarding compassion fatigue and to develop a comprehensive definition of this concept based on their professional experiences.</p> Methods <p>Employing a conventional qualitative content analysis approach, 17 Iranian palliative care nurses were recruited through purposeful sampling. Data were analyzed using the Elo and Kyngäs (2008) method, ensuring a systematic and rigorous examination of the participants’ narratives. Ethical approval was obtained from the Ethics Committee of Tarbiat Modares University, and written informed consent was secured from all participants prior to data collection.</p> Results <p>The analysis identified five central themes characterizing compassion fatigue: “emotional and psychological pressure,” “reflection of the patient’s pain and suffering,” “imbalance in empathy with the patient,” “exacerbation of physical and psychological complaints,” and “reduced vitality.”</p> Conclusion <p>These findings illustrate how compassion fatigue undermines a nurse’s ability to deliver empathetic and ethically sound care, often resulting in caregiving with a hardened heart. The study emphasizes the critical need to define and monitor compassion fatigue systematically, enabling nursing managers to identify at-risk nurses and implement targeted individual and organizational interventions. By addressing compassion fatigue proactively, healthcare systems can mitigate the risk of non-empathetic, dehumanized, and emotionally detached care, thereby enhancing both nurse well-being and patient outcomes.</p> Clinical trial number <p>Not applicable.</p>