In the data mining (or machine learning) community, as you can expect, the term learning is often used. As a consequence, it is explained in many books, mainly with different definitions. Therefore, it is often difficult to find a clear and understandable definition for the term learning. Across my readings, I found the following definition as the most clear one:
“Learning is the improvement of performance in some environment through the acquisition of knowledge resulting from experience in that environment” (1)
Although very informal, it explains clearly the meaning of learning for the data mining community.
(1) Langley P., Elements of machine learning, Morgan Kaufmann Publishers, 1996.