Rimorso translates to "remorse" or "regret". It's a strong emotional word that describes a deep feeling of guilt or distress arising from a past action.
In Vasco Rossi's song, the narrator sings about his partner's potential betrayal, stating, "E lo farai senza neanche rimorso" (And you will do it without even remorse). This highlights a chilling aspect of the relationship, suggesting a lack of empathy or feeling on the part of the betrayer, making the word particularly impactful and intriguing in this context.