Marble-hearted is a term used to describe a person who is cold and unfeeling. However, there are several synonyms that can be used to express this same sentiment. Some alternative terms include callous, uncompassionate, indifferent, heartless, and unfeeling. Each of these words conveys a sense of emotional detachment, and can be used to describe individuals who lack empathy or sympathy for others. While each of these terms may have a slightly different connotation, they all convey the same basic idea of a person who is uncaring and unresponsive to the emotional needs of those around them.