The word "zikurat" refers to a type of ancient Mesopotamian stepped pyramid. While there are not many synonyms for this specific term, there are related words that can be used in place of it. For example, one might use the word "pyramid" to describe a structure that is similar to a zikurat. Other related words might include "temple," "monument," or "tomb." Each of these words is associated with ancient structures and can be used to describe a zikurat or a similar type of building. Depending on the context, some synonyms may be more appropriate than others.