"Great big" is a colloquial and informal way to describe something as large or significant. However, it can become repetitive and monotonous to repeatedly use the same phrase. Thus, it is essential to have a diverse vocabulary and be aware of different synonyms for "great big." Other ways to describe something as big or significant include: colossal, enormous, massive, substantial, sizable, considerable, gigantic, mammoth, immense, and vast. Each of these synonyms adds a unique touch to your writing or speech and helps to create a more compelling narrative. Additionally, a varied word choice can keep readers engaged and interested in your content.