The word "noncasual" refers to something that is serious, formal, or structured. Some antonyms for "noncasual" include casual, informal, relaxed, laid-back, easy-going, and nonchalant. These words describe a more relaxed and informal environment or atmosphere. They suggest that there is no need to follow strict rules or adhere to formal etiquette. While noncasual indicates a certain level of decorum, these antonyms suggest a more relaxed approach. These words are often used to describe dress codes, social events, and workplace culture. In contrast to noncasual, they suggest a more comfortable, approachable, and friendly environment.