What term describes an irregular cardiac rhythm?

The term that describes an irregular cardiac rhythm is "arrhythmia." This term encompasses a wide variety of irregular heartbeats that can occur when the electrical impulses that coordinate heartbeats do not function properly. Arrhythmias can manifest in many forms, including rapid beats, skipped beats, or other variations that do not follow a regular pattern.

In contrast, tachycardia refers to a heart rate that is abnormally fast, while bradycardia indicates a heart rate that is unusually slow—neither specifically describes irregular rhythms. Atrial fibrillation, specifically a type of arrhythmia, is characterized by rapid and irregular beating of the atria, making it a specific instance rather than a general term. Therefore, "arrhythmia" is the broad and accurate term that encompasses any irregularity in the heart's rhythm.