I think we can all agree that these are hills:
Image from Wikipedia
They're kinda gentle, not too tall, and altogether nice-looking. But it's always bugged me that I can't come up with an objective definition for the word. Is that little bump in my lawn a hill? It's gentle, not too tall, and altogether nice looking. But I still wouldn't call it a hill.
Is there a widely accepted definition for 'hill'?