The antonyms for the word "nonrational" are "rational," "logical," "reasonable," and "sensible." These words refer to thinking or decision-making processes that are based on sound reasoning and evidence rather than emotions or instincts. A rational thought process involves the use of objective criteria to arrive at a conclusion or decision, while a nonrational process may be influenced by biases, preconceptions, or other subjective factors. In everyday life, we often make choices based on a mix of rational and nonrational factors, but it's important to recognize when our thinking is being guided by emotions or other nonrational influences.