What does metaphor mean?

A metaphor is just a comparison that doesn't use like or as. Example: She was a rose, beautiful, but covered in thorns. The girl isn't literally a rose covered in thorns. She's actually a beautiful girl who you need to be cautious of. Another example would be, My love was a burning fire that no amount of firemen could detain. It's not literal. It just means the person loves someone/thing a lot. Just tell me if you need more examples.