The word "asudden" means suddenly or unexpectedly. Therefore, antonyms for "asudden" would be words that indicate predicting or gradualness. These words include slowly, steadily, gradually, progressively, methodically, chronologically, and systematically. These antonyms suggest a deliberate process and predictable changes, as opposed to an abrupt or instant occurrence. Using these words in place of "asudden" would add a sense of planning and control to the sentence. For example, "The storm didn't approach asudden; the clouds gathered methodically, and rain began to fall gradually.