If your content includes a term that deserves more than a few words for a definition, create a page for the term then tag it with an underscore and the first letter of the term. The term will then appear in the site's Glossary.
For example, a glossary page for Twitter should be tagged as _t plus whatever else is appropriate.
Of course, this raises the question of how to create a new page in the first place. The easiest way to create a new page for the term is to enclose it in triple square brackets like this [[[eigenvector centrality]]]. Once you save your work, a red link is inserted to the nonexistent page. Simply click on the link to create the new page.