The word "wast nervous" doesn't exist, there's no meaning to it. However, if we consider the word "wasn't nervous" instead, a few antonyms that could be used are confident, calm, relaxed, collected, composed, assured, self-assured, and poised. These words denote a state of being free from worry or anxiety, instead exuding an air of certainty and control. So, someone who "wasn't nervous" could be described as either displaying one or more of these traits, depending on the context. It's important to note that choosing the right antonym for a word is crucial in effective communication.