Fictitious means made up and passed off as real. Not honest invention — a false claim.
That is what separates it from fictional, since a fictional character belongs openly to a story and a fictitious name is one somebody used to deceive. Law and journalism keep the distinction carefully, and fictitious invoices, fictitious employees and a fictitious address all describe fraud. The word is formal. Made-up and invented are the plain alternatives and neither carries quite the same accusation.
1adjectivefictitiousInvented and falsely presented as real.
“The claims were supported by fictitious paperwork.”
Also accepted in games: made-up, invented
Latin
fictīcius
English, today
fictitious
Borrowed from Latin fictīcius.
Etymology from Wiktionary, CC BY-SA