Forehead
Sure, this forehead is a bit square, but that's because it's the top part of the head (冂) radical. This is just the forehead part of that! You can even imagine this as the forehead of Frankenstein's monster, since his forehead was pretty square too.
Also, don't confuse this for a roof. You know this is a forehead and not a roof because this doesn't have a cute little chimney sticking out of the top. Foreheads definitely don't have chimneys.