The word "Munchhausen" refers to someone who tells tall tales or exaggerates about their experiences. There are many synonyms for this word, such as a fibber, storyteller, liar, embellisher, or fabulist. Other words that could be used to describe someone who makes false claims might include braggart, pretender, impostor, or phony. Someone who consistently exaggerates or tells falsehoods might also be described as a fraud, charlatan, or swindler. While these words each have slightly different connotations, they all describe someone who is not trustworthy in their claims or statements.