Yes, " enormousness" is an actual word in the dictionary.

没错，“庞然大物”在字典里本身就是一个单词。

And here we have " enormousness" : " The enormousness of the pyramids must be seen to be believed" , not the " enormity" .

我们还有“庞然大物”这个词：“你必须要相信金字塔就是个庞然大物”，而不是“罪大恶极”。