Coevality means the state of being of the same age or time period. Antonyms, on the other hand, are words with opposite meanings to a given word. Hence, antonyms of coevality would be words that convey a sense of differences in age or time period. Some antonyms of coevality include antiquity, modernity, prehistory, future, past, and posteriority. Antiquity refers to the ancient or old times, while modernity describes the state of being current or up-to-date. Prehistory denotes the time before written history, and the future relates to events or time to come. Past refers to prior events or times, and posteriority describes the idea of coming after a particular event or period.