There are several synonyms for the word "bisonant," which means having a booming or thunderous sound. Some alternatives to this word include resounding, booming, thundering, deafening, powerful, and loud. These words all convey a similar meaning to "bisonant" and can be used interchangeably depending on the context and tone of the sentence. Whether you're trying to describe the roar of a waterfall or the thunder of an approaching storm, these synonyms offer a wide range of options to accurately capture the sound in your writing.