diff --git a/Glossary-of-Terms.md b/Glossary-of-Terms.md
index 04a0803..279d179 100644
--- a/Glossary-of-Terms.md
+++ b/Glossary-of-Terms.md
@@ -7,11 +7,15 @@ The collection of core libraries that make up the framework
 **Essentials Plugins**
 SIMPL# Pro libraries that reference the Essentials Framework and are loaded at runtime to add or extend functionality
 
+**PepperDash.Core**
+A SIMPL# utility library referenced by Essentials Framework.  
+
 **Assembly**
  An assembly is a file that is automatically generated by the compiler upon successful compilation of every . NET application. It can be either a Dynamic Link Library or an executable file. It is generated only once for an application and upon each subsequent compilation the assembly gets updated.
 
 **Device**
 A base class, defined in the PepperDash.Core library.  It can represent a physical device, or a virtual device or behaviour.  Generally, most new classes defined in the Essentials ecosystem should derive from Device.
 
-
+**IKeyed**
+An important interface defined in PepperDash.Core that requires a string property named Key, whose value must be unique.