Malarkey is ridiculous or meaningless talk. You might feel strongly that your friend's excuses for not coming to your birthday party are just a bunch of malarkey.
You can generally use the word malarkey to mean "nonsense" or "hogwash." If you feel like a classmate is using big, impressive words and speaking in a deliberately complicated way to say something relatively simple, you can dismiss it as malarkey. And one political party might be quick to call an opponent's platform pure malarkey. You can also spell it malarky — both versions are an American invention from the 1920s.