Bogus means fake, phony, or not genuine. When something is bogus, it's pretending to be real but isn't. A bogus excuse for missing homework is one that's made up or dishonest. A bogus claim about a product means the advertisement is lying about what it can do.

The word often carries a sense that someone is trying to trick or deceive others. If a website makes bogus promises about making you rich overnight, it's deliberately misleading people. When your friend tells you a bogus story about why they can't come to your birthday party, you might suspect they aren't being truthful.

Kids sometimes use bogus more casually to mean unfair or disappointing, like calling a teacher's new seating chart “totally bogus” when you get separated from your best friend. In this sense, it just means you think something is bad or unjust, even if nothing fake is involved.