Substitute for is a phrase that is commonly used in English language. It is used to indicate an alternative option to an item, ingredient, or material that is unavailable or unsuitable. There are many synonyms for substitute for that can be used interchangeably. Some of these synonyms include replacement, alternative, stand-in, surrogate, backup, fill-in, proxy, and stand-in. Each of these synonyms carries a slightly different connotation, but they all convey the idea of something that can be used in place of another. Using synonyms can help to add variety and precision to your writing, making it more engaging and effective.