The word "sub" has many synonyms that can be used interchangeably. Some of these synonyms include substitute, replacement, alternator, stand-in, deputy, proxy, understudy, and backup. These words can be used in a variety of contexts, such as in sports, where a substitute player comes on to replace another player, or in business, where a backup plan is put in place to replace the primary plan if it fails. The word "sub" is commonly used in the sandwich or submarine sandwich context, where it can be substituted with terms like hoagie or hero. In the end, using these synonyms can help create diverse, effective, and more interesting conversations.