Organic growth is increase in revenue or earnings generated by the existing business — winning more customers, expanding within accounts, launching products, raising prices — as opposed to growth bought through acquisition. It reflects the operating performance of the assets already owned.
Organic growth is distinguished from inorganic growth (growth from acquisitions) because the two demonstrate different things. Reporting acquired revenue as organic performance overstates operating skill: the distinction, as the saying goes, is the difference between running the business better and having a budget to go shopping. Separating the two is essential to understanding how a company is actually creating value.