Update 1 December 2022: You may want to check out a newer version of this figure that I made for my latest book.
While reading in The biophysical foundations of human movement, I came across a nice illustration (adapted from Zeigler 1990) of the relationships between multi-, cross- and interdisciplinarity. These terms are often used, and I think it helps to have a visual guide for separating them.
The idea of the model is that when a field becomes more multidisciplinary it can eventually move towards becoming more cross-disciplinary and finally interdisciplinary. Thinking about the two fields that I feel the mostly associated with myself, i.e. music cognition and music technology, I am uncertain as to which of these categories they belong to. Although we all strive for interdisciplinarity, I still feel that the fields are somewhat polarized and that traditional disciplines (e.g. music theory, psychology, informatics) are still clearly visible. This could mean that the fields are still multidisciplinary and/or cross-disciplinary.