Definitions and categories can create headaches for many writers. Not just definitions in the books, but regarding the books themselves. At some point in time, every author needs to look at their work and decide, "What is this?" If you look at Amazon's category system, it fills pages, and the category you want usually doesn't exist.
I generally tell people I write science fiction romance or contemporary romance. For me, personally, the definition romance means the story has an element of people meeting and caring for each other. It doesn't necessarily have to be explicit sex. In my world, there's a special category for explicit books, called erotica. This is my definition, and not necessarily anyone else's.
I'm talking about this today because I recently submitted a short story to an anthology, and it was refused on the grounds of not containing a romantic element. The main character meets a girl, and they start caring for each other. It's been a year since I wrote this and I don't remember all the details, but I'm pretty sure they kiss, and I intended for the story to end with readers having a feeling of these characters getting together in the near future. To me, that's romance. To this publisher, it wasn't romance at all.
This is interesting, because definitions are so subjective. In my world, the main motif of a book doesn't necessarily have to be about people falling in love to be a romance. I mean, these ingredients have to be there, but romance is something that happens every day in life, while people go about their business of living. It's usually not a matter of, "Hey, today my main objective will be falling in love." Other people have another definition.
According to dictionary.com, the definition of romance is, "A feeling of excitement and mystery associated with love."
What's your definition? Is it about feelings, flirting, sex...? I'd love to hear what you think!