Depends, what does the OED say about leaping seconds? This may turn out to be just wrong. :D Anyway, I just realized that purest is also in the dictionary. So

Depends, what does the OED say about leaping seconds? This may turn out to be just wrong. :D Anyway, I just realized that purest is also in the dictionary. So purest is good, ultrapure is bad... And if pure is 100% then purest is... 100er%?