As someone who had written lots of XHTML in the past, not having closing tags makes my eyes twitch like Scrat in Ice Age. I even occasionally write `<br>` like `<br/>` out of habit.
<table><tr><th>Term 1<td>Definition 1
<tr><th>Term 2<td>Definition 2
</table>
<dl><dt>Term 1<dd>Definition 1
<dt>Term 2<dd>Definition 2
</dl>but then you can always use HTML tables in markdown and Pandoc transforms it just fine