Someone who can’t keep a beat is probably a bad dancer. They’re also arrhythmic, which is an adjective that means having no rhythm at all.
Most people have a steady heartbeat, ticking one pulse after another like a clock. But if you have an arrhythmic heartbeat, better call a doctor!. An arrhythmic heart beats randomly, without any regular pattern. The word can be tough to spell, so one trick is to start with the word rhythm, then add the prefix ar- (meaning “without”) and the suffix -ic (“characterized by”). Spell it that way, and you’ve got the definition memorized too: "characterized by being without rhythm."
