Some of you have asked what a novella is. I suppose one could say that it is a short novel. Without getting into tedious things such as word counts, suffice it to say that a novella is longer than a short story and a novelette, but shorter than a novel.
You could definitely kill a bug with a printed novella, and perhaps you could maim a smallish rodent, but you would be hard pressed to dispatch cattle with it.
These are the numbers that SFWA uses:
- Novel: a work of 40,000 words or more
- Novella: a work of at least 17,500 words but under 40,000 words
- Novelette: a work of at least 7,500 words but under 17,500 words
- Short story: a work of under 7,500 words