Wet Ingredient

Decided to investigate an interesting cooking fact this morning,
one that Chef John has alluded to in some of his cooking videos:
for some purposes, sugar is considered a wet ingredient. How
could this be?

Clearly, white sugar is a solid. But in baking,  it interacts with flour to
promote the formation of gluten (sticky starch). If, when assembling a
baked good such as muffins, one mixes the sugar with the liquid ingredients,
it will be less likely to form this gluten, and the resulting pastry will be lighter.

Voilà, sugar is a wet...

http://www.finecooking.com/article/how-is-sugar-wet