What is a fiction story called, which is larger than a short story, but smaller than a novel?

Question

Imagine I write a work of fiction, which is larger than 10.000 words (short story), but smaller than 80.000 words (novel). The external genre is thriller, the internal one -- disillusionment plot.

What do I call such work so that readers have the right expectations regarding its size?

Possible answers:

• Novella: Works between 17,500 and 40,000 words
• Novelette: Between 7,500 and 17,500 words
• This article claims that everything larger than 40,000 words is a novel (personally, I'm not sure about that)

Answer 1

There are multiple examples of novels that are little over 40,000 words. Ray Bradbury's Fahrenheit 451 is 46,118 words. Douglas Adams's The Hitchhiker's Guide to the Galaxy - 46,333 words. Erich Maria Remarque's All Quiet on the Western Front is ~60,000 words. All are, rather obviously, novels. (Source) Which indicates that your assumption that a novel needs to be over 80,000 words is mistaken.

For shorter works, the source you provide is a good guideline. In particular, this is the guideline followed by the Hugo and Nebula awards, (but notably, other awards use slightly different upper margins on a novella's length. Source) That said, Hemingway's The Old Man and the Sea is routinely featured on "best novel" lists, although it is merely 26,601 words - on the lower side of the 'novella' length.

I have seen the term short novel used sometimes, to describe a work that's comparatively short for a novel. However, I found no formal definition of the term.