The phrase "by fluke" refers to something that happens purely by chance or luck. There are several synonyms for this commonly used phrase, such as "by chance", "by accident", "by coincidence", "unexpectedly" and "fortuitously". These phrases can be used interchangeably with "by fluke" in different contexts to convey the same meaning. Other synonyms for "by fluke" include "serendipitously", "happenstance", "randomly", and "unintentionally". These synonyms can enhance the vocabulary and add variety to writing and expression. Thus, by using these synonyms, one can convey the meaning of chance occurrences with more precision and depth.