Side issues refer to any topics which are not directly related to the central subject of a discussion or argument. Synonyms for the term 'side issues' include peripheral issues, tangential topics, irrelevant matters or auxiliary concerns. These synonyms are often used when describing minor issues that are not crucial to the main topic. Other appropriate terms that can be used in lieu of 'side issues' include secondary concerns, minor details or extraneous elements. Regardless of what phrase is used to describe a side issue, it's important to identify and differentiate it from the main issue at hand to keep discussions focused and on track.