The word "astrodome" is a proper noun used to refer to a specific stadium located in Houston, Texas. However, there are several synonyms that can be used to refer to similar types of sports facilities. One synonym is "stadium," which is a large venue designed for sporting events. Another synonym is "arena," which typically includes a central area for events surrounded by spectator seating. "Dome" is also used as a synonym for "astrodome" because of its unique domed roof. Finally, "ballpark" is a commonly used term for baseball stadiums, which are often similar in design to astrodome-style facilities.