What does "knock it off" mean? Also, as a compound word, what does the suffix "-off" mean?

Native speaker’s answer
Rebecca
"Knock it off" is an idiom! It's another way of saying "stop it" or "quit it". You say it when you are annoyed with what someone is saying or doing. In this context, "off" is not a suffix. "Off" as a suffix refers to a competition or contest! Ex: Knock it off, Steve. That's so annoying! Ex: Drake, knock it off! Your singing is too loud. Ex: Let's have a dance-off. => dance competition Ex: Are you ready for the cook-off? I'm gonna win.