It's a little bit of both.
a sweet wine quenches thirst, and a dry wine leaves your tongue dry
Chianti is a dry red wine.
Semillon is a type of grape. Semillon is used to make the sauternes wines, which are sweet wines, usually called "dessert wines" because they are good "companions" to a dessert.
Riesling is usually semi-sweet, but it is available in dry varieties as well.
Roasted Leg of Lamb
The Differences Between Sweet and Dry Wines
How to Pay Attention to Wine Acidity and Sweetness
How to Pair Wine by Practice and Experiment