Canonical Data Model Help

I'm tasked with showing a model (from a business perspective) how 4 systems are being incoporated into one model (like a common data model). The data model is very high-level (non technical) and representing that information in a data dictionary. I'm getting stuck on how to represent it in a data dictionary because I have data coming from multiple systems. How do you represent the same data element from different systems in a way that makes sense and looks good and provides explanation on what the particular field means from a business perspective? Any examples would be greatly appreciative and/or a place to look on the internet anywhere or particular site?

Thank you!