(slang) stop!, stop what ever you are doing!to deconstruct/take apart a box - "Make sure you break down the boxes before you go, Tom."to dance/begin dancing/dance wildly - In his song "U Can't Touch This" MC Hammer says, "Break it down." Note that this is always "break it down" and not "break down".to explain something - "Could you please break this down for us? We don't get it."to stop working/functioning properly - "My car broke down last night and now it's in the shop getting fixed." or "Your engine is going to break down if you don't change the oil."to freak out or struggle emotionally ("break down" or "breakdown") - "I'm having a nervous breakdown! Help me!" or "I'm breaking down emotionally, Sally. I think I need to see a psychologist."