"At one swoop" is a phrase commonly used to indicate the completion of a task or action all at once. While this phrase is quite common in the English language, there are several synonyms that can be used in its place. Some examples include: in one fell swoop, all at once, suddenly, at a stroke, in a single blow, at a blow, and all together. These synonyms accurately convey the same meaning as "at one swoop" and can be used interchangeably to add variety to your writing. Whether you're writing an essay, a blog post, or a novel, using these synonyms can help keep your writing interesting and engaging.