The growing body of research on compassion has demonstrated its benefits for healthcare and wellbeing. However, there is no clear agreement about a definition for compassion, given the novelty of the research on this construct and its religious roots. The aim of this study is to analyze the mental semantic construction of compassion in Spanish-speaking women breast cancer survivors, and the effects of the Cognitively-Based Compassion Training (CBCT®) on the modification of this definition, compared to treatment-as-usual (TAU), at baseline, post-intervention, and six-month follow-up. Participants were 56 women breast cancer survivors from a randomized clinical trial. The Osgood’s Semantic Differential categories (evaluative, potency, and activity scales) were adapted to assess the semantic construction of compassion. At baseline, participants had an undefined idea about compassion. The CBCT influenced subjects’ semantic construction of what it means to be compassionate. Findings could lead to future investigations and compassion programs that adapt to a specific culture or population.