"Strictly business" is often used to describe something that is done in a professional and serious manner, with no room for personal feelings or emotions. However, there are a variety of antonyms that can be used to describe the opposite of "strictly business." These include terms such as "casual," "informal," "lighthearted," "relaxed," "friendly," and "personal." These words suggest a more relaxed and informal approach to doing business, where personal connections and relationships play a more significant role. While being "strictly business" can be useful in some situations, it's important to be able to adapt and use a more casual, friendly approach to building better relationships with clients and colleagues.