Final answer:
The term that describes the space between 2 cardiac cycles in an ECG is the PR interval. It measures the duration from the beginning of atrial depolarization to the initiation of the QRS complex.
Step-by-step explanation:
The term that describes the space between 2 cardiac cycles in an ECG is PR interval. The PR interval measures the duration from the beginning of atrial depolarization (the P wave) to the initiation of the QRS complex. It is clinically relevant as it helps identify any delays in the passage of electrical impulses through the heart.