General terms:
* Novel: This is the most common term for a long work of fiction, typically over 40,000 words.
* Long story: This is a more general term that can encompass a variety of lengths.
* Epic: This term is often used for stories with grand scope, heroic characters, and complex plots, though it's not limited to a specific word count.
* Saga: This term is often used for stories that span generations or follow a long historical period.
Genre-specific terms:
* Roman à clef: A novel in which real people and events are thinly disguised as fictional characters and situations.
* Bildungsroman: A novel that focuses on the development of a character from childhood to adulthood.
* Gothic novel: A novel that features elements of horror, mystery, and suspense.
* Historical novel: A novel that is set in the past and often incorporates real historical events and figures.
* Science fiction novel: A novel that explores the future, technology, and space.
* Fantasy novel: A novel that features magical elements, mythical creatures, and other fantastical concepts.
Other terms:
* Novelette: A long story, usually between 7,500 and 17,500 words.
* Novella: A long story, usually between 17,500 and 40,000 words.
* Book: A general term for any bound work of writing, including fiction and nonfiction.
Ultimately, the best way to describe a long piece of fiction is to consider its specific content and length.