The word "illusional" refers to something that is based on an illusion or false perception. Therefore, antonyms for "illusional" would be words that describe something that is real, concrete, or true. Examples of antonyms of "illusional" might include actual, factual, realistic, tangible, verifiable, and substantial. These words suggest that something is based on evidence or facts, rather than a fantasy or delusion. Other antonyms for "illusional" might include objective, nonfiction, proven, empirical, or observable. In general, words that describe things that can be seen or experienced in the real world are opposite in meaning to illusional.