(WSJ) - I RECENTLY TASTED a bottle of Chablis described by its accompanying fact sheet as "delicate, rich, rather mineral and dry." I understood the meaning of each adjective—except for one. What exactly is a "mineral" wine, let alone a "rather mineral" one?

While "minerality" has long been employed as a wine descriptor, it has only recently become quite popular. "It's a word everyone's using for everything," said Chablis producer Fabien Moreau, who started seeing its use rise around five years ago.

The word is popular among winemakers, wine retailers and sommeliers, not to mention wine drinkers, wine critics and wine columnists. Full disclosure: I've used it pretty often myself, mostly to describe wines with flavors of slate or flint or wet stone (though there is nothing of any of those elements in a wine—and those terms are up for debate, too). Perhaps minerality could be described as the meeting point of dry and wet.

Unlike other words that describe the taste of wine, such as "oaky," "flabby" or "bitter," a wine that is "minerally" is universally understood to be good. But what does everyone mean when they say it?

Doug Tunnell, proprietor of Brick House Wine Company in Newberg, Ore., makes wines that critics regularly describe as "minerally." Mr. Tunnell thinks minerality (which he calls the "M word") was created to capture an experience that's impossible to define. (It isn't even in Webster's dictionary.) Yet Mr. Tunnell thinks minerality still has credibility "not as a word of science but art."