“Round” is a tasting note that is completely subjective. A beverage tasting “round” is not only one of the most subjective tasting notes on the planet, it’s also one of the most used, and almost impossible to define in one way.
Substitutes for the word round can be “smooth,” “velvety,” “plush,” “opulent,” “supple” — they all sort of mean the same thing, which is that the liquid on your palate tastes full (there’s another one), and easily spreads across the tastebuds on your tongue.
What may be round or smooth to you is quite possibly very different from someone else’s palate, which is why it’s a very confusing tasting note to share with someone. So, the next time someone tells you their beverage tastes round or smooth, ask them what they mean by saying that. Is the wine lower in tannin, fruitier, or sweeter? Does the beer have less hops character and more malt flavor? Maybe the whiskey has less of a burn?
Then, you’ll hopefully have a better understanding of the taste or sensation they’re experiencing.