And this isn’t quite a contronym, but “silly” originally meant “blessed.”
“Silly goes the other direction,” Curzan explains. “Silly goes all the way back to Old English, when silly meant happy or blessed.” This positive term quickly changed. Silly became a synonym for innocent or harmless, and then became an adjective for something or someone worthy of sympathy.
Something we feel sympathy for is something that’s weak. And something that’s weak is unsophisticated. Finally, silly went on to mean ignorant and lacking sense.
A quantum leap is often used to emphasize a large step forward, however in physics it means the smallest possible change of state.
And this isn’t quite a contronym, but “silly” originally meant “blessed.”
https://www.michiganpublic.org/arts-culture/2013-10-27/the-changing-meanings-of-nice-and-silly
And, as that same article said, “nice” used to mean what silly means today.
And thanks to internet culture blessed now can mean something similar to silly.
That’s nice, dear.
I’m generally a nice person. Not very silly though.
Yeah I can relate.