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.

Nico Danneberg

Adds explaining tooltips querying their content from a <a href="https://www.mediawiki.org" title="see MediaWiki docs" rel="nofollow ugc">MediaWiki</a> installation, e.g. <a href="https://www.wikipedia.org" title="see the well-known Wikipedia" rel="nofollow ugc">Wikipedia.org</a>. Therefore shortcodes can be used in Posts and Pages to mark keywords and link them to public Wiki pages. The well-known package of <a href="https://calebjacob.github.io/tooltipster/" title="Tooltipster rocks :)" rel="nofollow ugc">Tooltipster</a> is used to create the nice and themable tooltips.
Main features of the current version are:
<ul>
<li>Setup at least one wanted Wiki base and several other options at a backend page</li>
<li>Integrate the Wiki tooltip in Posts and Pages using a handy popup in Gutenberg editor or simple shortcodes</li>
<li>Shortcodes can be created by a <a href="https://codex.wordpress.org/TinyMCE" rel="nofollow ugc">TinyMCE</a> plugin, too</li>
</ul>

WP Wiki Tooltip

Adds explaining tooltips querying their content from a MediaWiki installation, e.g. Wikipedia.org.

Wp-Wikipedia-Excerpt vs WP Wiki Tooltip