If 1 USD were to equal 90 yen, would this mean that the dollar is weaker then the yen.

I understand that this isn't likely to happen soon, but considering the going rate for items in Japan, I assume that if the dollar were to be the equivalent of 90 yen it would be considered "weaker" then the yen. Assuming that 100 should be the standard equivalent for the value the currency holds in the country. Is that line of thinking arbitrary? I would love for someone to explain why or why not.