The phrase "basis for discussion" refers to the topic or subject that is being used to initiate a conversation or debate. In order to add variety and depth to your discussions, there are numerous synonyms that can be used to convey the same meaning. Some of the commonly used synonyms for "basis for discussion" include "talking point", "focus of discussion", "starting point", "foundation for discourse", and "subject of debate". Other possible alternatives include "theme", "topic", "subject matter", and "agenda item". These expressions will allow you to convey the same idea in different ways while keeping your conversations fresh and engaging.