Coseismic refers to something that is associated with an earthquake. The antonyms for this word are unrelated to earthquakes, such as peaceful, calm, tranquil, and still. These words imply a state of serenity and absence of any shaking or movement. Other antonyms for coseismic could be static, motionless, quiet, and dormant, all denoting a state of stability and a lack of seismic activity. In contrast, the word coseismic is often used to describe the impact of earthquakes, including destruction, loss, and chaos. Therefore, its antonyms have positive connotations of stability, safety, and peacefulness.