Antonyms are words that have opposite meanings to each other. If the word "gives go ahead" means to approve or allow something to happen, then antonyms could be words that mean the opposite of this. These might include words like forbid, block, deny, reject, prevent, or prohibit. Each of these words implies a sense of limitation or restriction, suggesting that something is not permitted or not allowed to take place. Thus, while "gives go ahead" is a positive phrase that signals approval, antonyms might be used to express negativity or disapproval, indicating that an action or decision is not supported or endorsed.