In fact, confectioners' sugar being colloquially called "powdered sugar" is disputed ... it's dusted with a fine mesh sieve.
Despite its very fine texture, you’ll notice that many recipes urge bakers to sift powdered sugar in a fine-mesh sieve or ...
The truth is, you can often ignore this step, which calls to push a dry ingredient through a sifter or fine-mesh sieve to ... such as cocoa powder, powdered sugar, cake flour, baking powder ...