Speech or writing that is nonsensical, overly complicated, or full of confusing jargon, to the point of being incomprehensible or unintelligible. Primarily heard in UK. Look, just skip the legal mumbo jumbo and tell me how much I'll be inheriting. My wife goes to this healer who just chants mumbo jumbo for half an hour. I think he's a con artist, but she swears that it helps her back pain.