If the default "it works" page has rounded corners and no text smaller than 32pt, it's a rails framework.

If I had to come up with a definition, it would be "Full stack web framework with sensible defaults, that emphasizes DRY and COC." As always, any time you reduce something, it's lossy...

I think you got two good answers. They aren't even conflicting, just presenting the two sides of the coin.