Flunk out is a common term used to describe the act of failing a course or program of study. However, there are several synonyms for flunk out that can be used to communicate the same idea in different ways. Some popular synonyms include fail, bomb, fall short, come up short, wash out, drop out, and be expelled. Each term carries a slightly different connotation, and the right choice depends on the context in which it is used. Overall, using synonyms for flunk out can help add variety and nuance to one's writing and speaking, while still conveying the message clearly.