expatiate

It’s all there in the Reuters reporting, and there is no need to expatiate on the obvious immorality of the operation, quite apart from its colossal stupidity.

Do not be afraid to expatiate on all the ways you are a bigger person — there are probably lots!

We took long walks in the botanical garden in the Bronx, where he could expatiate on every species of fern.

His writings expatiate on the idea.

It was suddenly cool to know stuff, to expatiate on the causes of the Spanish Civil War.