All right, let’s just dive right into this stupid thing.
Recently, a professional athlete was quoted in an article as saying I made the stupidest mistake. The athlete was talking about his personal life—his VERY personal life. (It’s hard to keep track these days, isn’t it?)
The superlative form of stupid is most stupid, as in I made the most stupid mistake, not stupidest. Stupidest can be heard and seen everywhere, but it’s wrong. (Please don’t ask me to roll out my entire exposition on why finding a word in a modern dictionary doesn’t make it legitimate, standard English. Paul and I have already paddled across that ocean several times.)
Stupid is just like lucid (same –id ending). The comparative form is more lucid, and the superlative form is most lucid. Likewise, the comparative form of stupid is more stupid, and the superlative form is most stupid. In fact, in general, –id words use more and most instead of –er and –est. (The water was more tepid, he was the most lucid, they could have been more candid, his reflexes have grown more torpid, the milk was the most rancid, his tongue had grown more acrid. No one would even think to say tepidest, lucidest, candidest, torpidest, rancidest, or acridest.)
Oddly enough, as many times as I’ve heard the word stupidest (and believe me, if I sold my soul to the devil in order to have eternal life, that wouldn’t be long enough for me to count the number of times that I’ve heard it over the past few years), I’m not sure that I’ve ever heard anyone use the word stupider (even though it is now given as an alternative form in some modern dictionaries!). Maybe that’s because people know how stupid the word stupider sounds and that the correct form is more stupid. Then why don’t they know how stupid stupidest sounds and that the correct form is most stupid?
Regardless, the aforementioned athlete may have made the most stupid mistake in his personal life, but he also made a mistake when he used the word stupidest.