(WSJ) - WHAT’S THE MOST common word oenophiles use—and misuse—to describe a wine? The answer might surprise you. According to several retailers, it’s “smooth.” Ian Dorin, wine director of the Wine Library, a large wine store in Springfield, N.J., told me, “It’s the 1,000,000%, single-most misused term of all time.”

Perhaps that’s because smoothness in wine is almost impossible to define. The adjective is so elastic that Gary Fisch, owner of the New Jersey-based Gary’s Wine & Marketplace chain, said that “no one really knows what it means.”

Many smooth-wine seekers are actually looking for wines that are sweet, said Mr. Dorin, citing examples such as the Zinfandel-based Apothic Red from California. Others want something with little or no tannins or acidity, according to Joe Salamone, head wine buyer of Crush Wine & Spirits in New York. Which in most cases translates as bland. Tannins and acidity can be off-putting—even painful—to certain wine drinkers. But these components not only enliven a wine, they lend it texture and complexity, and make it a good match with food. Try drinking a wine lacking both tannins and acidity, and you’ll see what I mean. There’s no tension, no uplift. The wine stays flat on your tongue.

Tim Finch, manager of K&D Wines & Spirits in Manhattan, said he has had customers scrunch up their faces as they describe the attributes of a wine they don’t want, suggesting in a physical fashion just how painful it is. They’re almost always talking about reds, he added—something other retailers found to be true as well. In the rare case when a customer uses “smooth” to describe an ideal white, it’s usually a “fancy way of saying creamy or buttery,” Mr. Dorin opined.

Whether they’re looking for someone to interpret their expressions or simply looking for guidance, smooth-wine seekers seem to talk to their merchants a lot. As Mr. Fisch of Gary’s Wine observed, “Smooth is a conversation opener.”

This might be because the word is not only hard to define but seems to rarely appear anywhere in the stores’ displays. I toured a number of wine shops recently looking for “smooth” on the sales placards and critics’ reviews attached to shelves and was hard pressed to find the actual word—which surprised me, given its popularity among wine buyers. Instead I only found synonyms like “plush,” “soft,” “supple,” “round” and, a particular favorite, “easy to drink.”

If “smooth” is a word that wine critics rarely employ, what about winemakers? Is it a term that they endorse or eschew? And what does it mean to them? I put the question to David Ramey of Ramey Wine Cellars in Healdsburg, Calif., whose acclaimed reds and whites have been called smooth by a few of the retailers I know.