The word "most beheaded" can be replaced with synonyms such as "most decapitated" or "most guillotined." While all the terms refer to the act of cutting off someone's head, they may be used in different contexts. "Most decapitated" may be used to describe a particular group or population that has suffered the most beheadings in a conflict or war. "Most guillotined" may be used to describe a historical period during which many people were executed by means of the guillotine, such as the French Revolution. The choice of synonym will depend on the specific context and tone of the writing or conversation.