Just like with wine, Dry is the opposite of sweet.
As a flavour descriptor, Dry is the description given to a spirit when there is an absence of sweetness to taste, but it’s worth noting this is may not be due to a lack of sugars, it could just be the presence of some other taste that masks sweetness. For example, Angelica root is a botanical that can give the perception of dryness to the finish of a Gin, quinine and wormwood do the same in other drinks, irrespective of their being a touch of sugar in the recipe.