A rebuttal is a response to an argument or criticism. Some antonyms for the word 'rebuttal' could include agreement, acceptance, acquiescence, or concurrence. These words suggest a lack of opposition or dispute, indicating that there is no need for a rebuttal. Another antonym could be indifference, implying that the argument is not significant enough to warrant a response. Additionally, submission or surrender can be antonyms for rebuttal, suggesting a defeat or concession. Depending on the context in which it is used, each antonym can convey a distinct concept and sentiment.