"For an instant" is a phrase that is often used in written and spoken English to indicate a very short period of time. However, there are several useful synonyms for this phrase that can help to make your writing or speech more varied and interesting. Some alternatives to "for an instant" include "briefly," "momentarily," "fleeting," "transiently," "temporarily," and "in an instant." Each of these words carries a slightly different connotation, which can help you to convey your meaning more precisely. By choosing synonyms for "for an instant," you can add depth and nuance to your writing, making it more engaging and effective.