graywolf has made some good observations about definitions appearing above the organic search results in Google. For example, if I search Google for, “what is plantar fasciitis” it returns:
Where the first entry is a Google dictionary item. When you click on it, 5 links to different definitions are displayed. The link in the first position is what gets displayed on the main search results page.
One thing I noticed, and it could be a cooincidence, is that all the pages listed had “Glossary” in the title tag, high up on the page and in the url.