Google used to provide links to definitions in the blue bar of the SERP.
If there was one term, the text "definition" would have a link to its definition.
If there was more than one term, each term would link to its definition.

Single term searches still seem to have a link to the definition.
Multiple term searches seem to no longer have links to definitions.

It's a pity. Heavy users don't like any dumbing down, but from Google's point of view every piece of screen real estate, even those little blue underlines, must justify its value to the "average user".

It did not use extra screen real estate. The words are still there, but they do not have links.

The links caused the SERP to consume some additional bytes.

> It did not use extra screen real estate.

That's right. I didn't use the word "extra".

But even the little blue underlines must deliver sufficient benefit to negate the extra visual clutter they add to the page.

Maybe Google noticed that the multi-word definition links were rarely clicked. In my experience, most regular users don't know that you can get definitions from Google, even for single words (and even though a "definition" link is right there on the results page).