When we talk about "big stars" in the entertainment industry, we usually refer to celebrities with immense popularity and success in their fields. However, there are various ways to describe these individuals using synonyms. For instance, you can use the term "superstar" to denote a prominent and highly-rated performer. The phrase "megastar" is another option to refer to an immensely popular celebrity. Additionally, you can use words like "icon" or "legend" to describe someone who has achieved incredible success and is highly respected in their field. Ultimately, there are numerous terms that can be used to describe "big stars" depending on the particular context and the impact they have made in their area of expertise.