<p>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.</p>
<p>The plan is to augment this with a mouseover popup containing an excerpt from the wikipedia page.</p>


Wp-Wikipedia-Excerpt

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

flashpixx

<p>The plugin is a Wikipedia plugin, for setting links to Wikipedia articles. The language and the description for every link can be set individually.</p>
<h3>Requirements</h3>
<ul>
<li>WordPress 3.2 or newer</li>
<li>PHP 5.3.0 or newer</li>
</ul>
<h3>Shortcode</h3>
<p>Add to your content of a page or article</p>
<pre>[[search tag]]</pre>
<p>Another way for using the Wikipedia call, is to use the additional syntax</p>
<pre>[[ article | view ]]</pre>
<p>creates a link to the article and within the content the view text is shown</p>
<pre>[[ language | article | view ]]</pre>
<p>creates a link to the article with the language and within the content the view text is shown</p>


Reference 2 Wiki

Creates links to Wikipedia with different languages

Wp-Wikipedia-Excerpt vs Reference 2 Wiki