"Mortal shame" can be replaced with several synonyms that convey a similar meaning. One such term is "deep embarrassment," which suggests a sense of humiliation and unease. "Egregious disgrace" also carries a similar connotation, emphasizing a significant error or sin. "Guilt-ridden shame" underlines a powerful sense of culpability and self-judgment, while "humiliating guilt" implies a similar level of disgrace and personal responsibility. Additionally, "unforgivable shame" denotes a severe and irreparable sense of wrongdoing. Overall, these synonyms indicate a profound and lasting sense of shame, with a powerful emotional impact that can be challenging to overcome.