Decollation is a term that refers to the act of beheading or cutting off the head. Some synonyms that can be used in place of decollation include decapitation, execution, guillotining, and scalpeling. Other words that can be used to describe the same act include beheading, chopping, truncating, severing, and cleaving. These words are commonly used in both formal and informal settings to describe the process of cutting off the head, whether in an execution scenario, surgical procedure, or in nature. However, it is important to note that the use of such words may be sensitive and should be used with caution.