Translation:What is the square root of nine?
The same thought crossed my idle mind. But maybe we should delete these idle comments.
I think it's like "square" or "squared". The table may be square, but the root (3) is squared (i.e. multiplied by itself). Visualize a 3x3 box, with an area of 9. If the question is what is the square root, you're really asking what do you get when you take a square with an AREA of 9 (9 "squared") and look for the length of one side. That's the square root because if three is squared (multiplied by itself), it's an area of 9.