By reason is a phrase commonly used in written and spoken English to convey an explanation, causality, or justification. However, there are several synonyms that can be used interchangeably with this phrase to add variation and nuance to your writing. Such synonyms include owing to, because of, on account of, due to, as a result of, given that, in view of, in light of, considering that, since, and thanks to. Each of these synonyms has its distinctive flavor and can be used according to the context and style. By using synonyms for by reason, you can avoid repetition, make your writing sound more sophisticated, and clarify your message to the readers.