Glossary Terms Hierarchy
A glossary is generally a flat collection of terms, as you may have any number of glossaries, you may include the terminology for particular domains in different glossaries. You may also include terms inside of a term, thus creating a hierarchy of terms.
Information note
Glossary hierarchies in the past were represented by folder-like objects called a glossary categories. Currently, though, hierarchies may be built up with terms, in this way those hierarchies may also have all the features of a term.