When it comes to synonyms for the word "underrates", there are several terms that can effectively express the same sentiment. "Underestimates" is a suitable alternative, encapsulating the idea of belittling or devaluing something or someone's worth or abilities. Similarly, "undersells" could be used to describe the act of downplaying or depreciating the value or significance of something. Another synonym is "diminishes", which conveys the notion of underestimating or reducing the importance, value, or recognition of a particular subject. Other words that could be used interchangeably include "downplays", "deprecates", and "disparages", all of which describe the act of undervaluing or understating someone or something.