Huh... I thought the novel mark was at 60k 
As a broad rule of thumb, how writers define "novel" tends to be 40k+ words, because various associations and awards come from times when this was the normal market convention.
But for the past several decades, publishers have established other lengths as "normal" for novels, so people who define "novel" based on their own experiences as a reader will generally not perceive something as a novel unless it falls at least close to those conventions. That's where longer definitions of "novel" tend to come from.
The "60k+" definition is a practical starting point for reader perception, though in practice, science fiction and fantasy tend to start at 80k-100k.
Some self-publishing authors choose to use terms based on reader perception, like one author who has used the term "novella" for works that are significantly shorter than other entries in a novel series, even if those so-called novellas are actually novel length. It's up to you if you go this route, use the market-based definitions, or use the more formal writer ones.
