A Novel is a book in most people’s minds. Saying “I wrote a novel,” and “I wrote a book” are synonymous with most of the population. Thus, saying “I wrote a novella” indulges in jargon, and jargon always sounds mildly pretentious to those outside of the group that invented it. Also, it sounds like “lesser novel”, which is what it is. Which is why I may start describing my novellas as “literary doodles”. It sounds more fun.
Dictionary.com ontologizes it as “a fictitious prose narrative of book length, typically representing character and action with some degree of realism.” I’m a bit skeptical of the last bit, as that seems to be a trait of the literary or social novel. But then how much realism is “some”?
And the “of book length” seems to ask as many questions as it answers. How long is a book? If a book isn’t long enough, does it cease to be a book? Did Dr. Seuss write bookellas?
The word “novel” derives from the Latin for “new”, which suggests a focus on current things. This may be the reason Sir Walter Scott distinguished the novel from the romance, which was supposed to be about matters marvellous in nature. This would mean that The Lord of the Rings would properly be termed a “romance”, which would no doubt please Tolkien. However, other european languages, such as French, use the word “roman” (or its equivalent) to mean “novel.”
So we’re back to Long Prose Fictional Narrative. Which is what most people mean. I love it when a plan comes together.