Which word indicates a sense of being unconcerned or casually confident?

The word "nonchalant" perfectly embodies a sense of being unconcerned or displaying a casual confidence. It describes an attitude characterized by a lack of anxiety or worries, often conveying a relaxed demeanor. For instance, someone who is nonchalant in a tense situation may appear calm and unfazed, suggesting that they are comfortable and at ease regardless of external pressures.

In contrast, the other words do not convey this sense of casual confidence. "Omniscient" refers to having complete or unlimited knowledge, understanding, or awareness, which does not relate to being unconcerned. "Venial" describes something that is pardonable or minor in terms of sin, offering no connection to confidence or demeanor. "Supercilious" conveys an air of superiority and arrogance, suggesting someone who looks down on others rather than being casually confident. Thus, "nonchalant" stands out as the word that most accurately reflects an unconcerned attitude.