Opinion is a subjective evaluation or viewpoint on a particular matter. Antonyms for the word "are opinion" can be objective, fact, or truth. These words represent ideas or concepts that have been proven to be real, accurate, and unbiased. Objective implies that something is fair, impartial, and based on facts. Fact refers to something that is known to be true and has evidence to support it. Truth represents a universal understanding of something that is indisputable. These antonyms emphasize the importance of basing one's beliefs on facts and evidence rather than personal biases or beliefs.