Comparative form of stupid: more stupid(adjective)
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Use "stupider" in a sentence
"The best evidence that we’re getting stupider is the fact that soccer is the world’s most popular sport ...."
"The only thing stupider is that it actually works because so many people’s machines are configured to be insecure by default."
"How much the more does a man who has passed the age at which we instinctively display them, a man who, for instance, has gone through the most burning moments with an icy countenance, execrate those same faults, if it is another man, younger or simpler or stupider, that is displaying them."