The word "prepare" often refers to getting ready for a particular task or event. Antonyms for this word would thus refer to the opposite action or state of being. Some possible antonyms for "prepare" include terms like "neglect," "ignore," "disregard," "disorganize," "improvise," or "spontaneous." While each of these words represents a different concept, they all stand as an opposite to the act of preparing or getting ready. In some cases, such as with the word "improvise," antonyms may imply that preparation is unnecessary, while in other cases, such as with "neglect," the lack of preparation may have negative consequences.