Enter the terms or
Concept Unique Identifiers
(CUIs) whose similarity or
relatedness you wish to compute into the fields labeled *Term 1* and
*Term 2*. You can enter any combination of terms or CUIs. For example:

- heart attack and skull
- C0018563 and C0037303
- hand and C0037303

You can than either calculate the two terms similarity or relatedness. A discussion of the difference between similarity and relatedness is here.

To calculate the similarity you have two options:

- SAB designates what UMLS source to obtain the hierarchical information
- REL designates what relation information to use from the designated source

To calculate the relatedness you also have two options:

- SABDEF designates what UMLS sources to obtain the definitions from
- RELDEF designates what relations to use to create the extended definiton