Thundercrack refers to a loud sound produced by lightning in the atmosphere. It is an intense noise that symbolizes power, passion, and energy. The antonyms for thundercrack could be silence, quiet, peace, calmness, stillness, tranquility, serenity, and hush. These words represent the opposite of the explosive, earth-shattering sound of thunder. They imply a sense of relaxation, serenity, and stillness, which is the exact opposite of the loud and tumultuous thunderclap. So, while a thundercrack may startle or even terrify some people, the antonyms for it offer a sense of peace and quietness that can be equally soothing.