Sure, how much is a cup of not-yet-melted butter?
I found a claim that it is 1/2 a pound which sounds about right, 227g gives a density a bit below 1 for 240ml. Good enough for brownies.
I looked up Wikipedia for the entertainment, I learned that the US has both legal and customary cups (are the latter than illegal?) Then there are metric and imperial cups, as well as Russian and Japanese: https://en.wikipedia.org/wiki/Cup_%28unit%29