Fictitious means made up or imaginary rather than real. A fictitious character like Sherlock Holmes never actually existed: Arthur Conan Doyle invented him for his detective stories. When someone uses a fictitious name, they're using a fake name instead of their real one.

The word helps distinguish between what's real and what's invented. Historical fiction novels blend real events with fictitious characters, so you might read about a made-up family living through the actual American Revolution. Sometimes people create fictitious scenarios to illustrate a point: “Let's imagine a fictitious school where homework doesn't exist.”

Notice that fictitious is different from fictional. While both describe things that aren't real, fictional usually applies to stories and characters in books and movies, things that are openly imaginary. Fictitious often suggests something pretending to be real when it isn't, like a fictitious business address or a fictitious expense report. If someone submits fictitious expenses to their company, they're claiming they spent money they didn't actually spend, which is dishonest and illegal.