Which term best describes an informal spoken exchange of ideas among individuals?

The term that best describes an informal spoken exchange of ideas among individuals is "conversation." This term typically refers to a casual interaction where people share their thoughts, opinions, and feelings without the structure or formality that might be found in other forms of communication. Conversations can range from light chatter to deeper discussions but primarily maintain an informal tone.

In contrast, the other terms have slightly different connotations. "Dialogue" often implies a more structured exchange of ideas, typically involving two or more individuals discussing a specific topic in depth. "Discourse" is typically used in more formal contexts, referring to extended communication or debate that occurs around a particular theme or topic in a broader social context. "Discussion" may also suggest a more organized exchange where people actively engage in deliberating a subject, often with the intention of reaching a conclusion or agreement.

Thus, "conversation" stands out as the most fitting term for an informal and natural spoken exchange.