The term "Soul Underground" is not widely recognized as an established concept, organization, movement, or cultural entity in available encyclopedic sources. Accurate information about its specific meaning, origin, or usage is not confirmed.
It may be interpreted contextually as a descriptive phrase combining "soul," often associated with a genre of music rooted in African American culture emphasizing emotional expression, and "underground," typically referring to subcultural or non-mainstream movements. In such a context, "Soul Underground" could hypothetically describe a niche or grassroots scene dedicated to soul music or soul-inspired artistic expression operating outside commercial mainstream channels. However, no verifiable references confirm the existence of a formalized group, event, or publication by this name.
Due to the lack of reliable sources, no definitive classification or historical background can be provided.