What term describes a rapid heartbeat?

The term that describes a rapid heartbeat is "Tachycardia." This condition is characterized by a resting heart rate that exceeds the normal range, typically defined as over 100 beats per minute in adults. Tachycardia can result from various factors, including physical activity, stress, emotional responses, or underlying health conditions. Understanding tachycardia is important in both clinical settings and for individuals monitoring their heart health.

The other terms listed refer to different conditions: "Cardiomegaly" refers to an enlargement of the heart, which can affect heart function but does not specifically describe the rate of heartbeat. "Bradycardia" indicates a slower than normal heart rate, typically fewer than 60 beats per minute, which is the opposite of tachycardia. "Tachypnea" describes rapid breathing rather than heart rate, thus is unrelated to the description of heartbeat rates.