Antonyms for "jacking up" would include lowering, decreasing, reducing, or diminishing. While "jacking up" typically refers to raising or increasing something, its antonyms refer to the opposite actions. For example, lowering the price of a product, decreasing the volume of music, and reducing the number of staff members are all actions that are opposite to "jacking up." Using antonyms to "jacking up" can help provide balance to language and help avoid repetitive or overused phrasing. It is important to choose the correct antonym to ensure that the intended meaning is clear and concise for the reader or listener.