A distinct set of concepts or thought patterns 1
A world view underlying the theories and methodology of a particular scientific subject. 2
A framework containing the basic assumptions, ways of thinking, and methodology that are commonly accepted by members of a scientific community 3

I’d add that the concepts construct a particular context around themselves and the result is a guideline for derivative thinking based on the starting points.

But perhaps my understanding of this concept is skewed due to its use in the programming world especially to describe the need for a paradigm shift in order to correctly understand and use tools which are based on (initially) foreign concepts.