The basic idea here is that you can easily link to the wikipedia entry for a given topic by putting the [wikipedia]topic[/wikipedia] tag into your post. The tag is replaced by a link that executes the wikipedia search form for that topic.
The plan is to augment this with a mouseover popup containing an excerpt from the wikipedia page.

Wp-Wikipedia-Excerpt

This plugin replaces [wikipedia]topic[/wikipedia] with a wikipedia search link for that term.

samwilson

The Embed Wikimedia plugin adds support for embedding photos from Wikimedia projects such as Wikipedia, Wikimedia Commons, and Wikidata.
It requires no configuration, and to use you just add a URL of any of the above sites on its own line in a WordPress post or page.
Development is on Github at <a href="https://github.com/samwilson/embed-wikimedia" rel="nofollow ugc">samwilson/embed-wikimedia</a>; 
please report all issues there.

Embed Wikimedia

The Embed Wikimedia plugin adds support for embedding photos from Wikimedia projects such as Wikipedia.

Wp-Wikipedia-Excerpt vs Embed Wikimedia