The continuum from unidisciplinary to transdisciplinary, reproduced with the permission of Dan Stokols.
The term "Transdisciplinary" was introduced in 1970 by Jean Piaget to describe a methodology that goes beyond any single discipline. It is often confused with the terms interdisciplinary, multidisciplinary, and cross-disciplinary. This is not the last word in the definition of transdisciplinary, but it is a helpful start:
Transdisciplinary is when people from multiple disciplines work jointly to synthesize existing disciplinary work and extends it into a shared framework that creates a new approach.
Interdisciplinary is when people from different disciplines work jointly, but do not develop a shared framework that synthesizes and extends their discipline-specific concepts and methods.
Multidisciplinary is when people from different disciplines work sequentially, with the goal of eventually combining results to address a common problem.
Unidisciplinary is when people from a single discipline work together to addresss a common problem.