The word "definite" refers to something that is clear, certain, or fixed. If we are looking for antonyms (words that mean the opposite) of this word, we can consider words that have a more vague or uncertain meaning. Examples could include words like undefined, ambiguous, unclear, imprecise, or indeterminate. These words suggest a lack of clear definition or certainty, and are often used to describe concepts or ideas that are hard to pin down. To use an example in context, we might describe a plan as 'definite' if it is clear and fixed, but 'ambiguous' if it is unclear or open to interpretation.