Final answer:
Cardiac standstill without discernible electrical activity is known as asystole, a condition where the heart completely stops beating due to the absence of electrical activity.
Step-by-step explanation:
Cardiac standstill without discernible electrical activity is known as asystole. Asystole is a condition where there is a total cessation of electrical activity in the heart, which means the heart ceases to beat and no pulse can be detected. This is different from ventricular fibrillation, where the heart still has uncontrolled electrical activity causing it to beat in a rapid, erratic manner, which is also life-threatening and considered a medical emergency leading to 'code blue' if not treated promptly.
In contrast, bradycardia refers to a slower than normal heart rate, and tachycardia refers to a faster than normal heart rate. These conditions differ from asystole in that there is still some electrical activity causing the heart to beat, even if at an abnormal pace.