Minimum Viable Product (MVP) in Lean or Hybrid Environments

When working in lean or hybrid environments, you'll often hear the phrase minimum viable product. What's the most minimuly featured thing you can build that will address the opportunity well for most of your target customers? You'l want to clearly define these situations to help everyone understand what the product will need to do when it is finished. Continuing our c and n example, if you went back in time and were working on the first version of c and n's mobile ap, what's the simplest ap you could build that would provide value to your customers?