The term phenomenology is used to describe a body of knowledge that relates different empirical observations of phenomena to each other, in a way consistent with the fundamental theory, but that is not directly derived from it.

For example, simple algebraic expressions can be used to model observations or experimental results about different lengths, masses, and time scales, despite the fact that the expressions themselves cannot be (or have not yet been) derived from the fundamental theory of that area of ​​knowledge.

Another way to describe phenomenology is that it is a middle ground between experiment and theory. It is more abstract and includes more logical steps than experiment, but is more directly related to experiment than theory.

The boundaries between "theory" and "phenomenology", and between the same and "experiment" are somewhat blurred and to a certain extent depend on the understanding and intuition of the scientist who describes them.

Most scientists would say that phenomenological modeling does not constitute an understanding of the phenomenon, but they would also agree that it plays a relevant role in science.