Define murmur.

Explanation

**Step-by-Step Solution:**

1. **Understanding Heart Sounds**: The heart produces two primary sounds known as "Love" and "Dove." The "Love" sound (first heart sound) occurs when the atrioventricular (AV) valves (tricuspid and bicuspid) close. The "Dove" sound (second heart sound) occurs when the semilunar valves close.

2. **Definition of Murmur**: A murmur is defined as an abnormal sound that occurs during the heartbeat cycle. It is a disturbance in the normal heart sounds (Love and Dove).

3. **Causes of Murmur**: Murmurs can arise from defects in the heart valves. When there is a defect in the AV valves or the semilunar valves, it can lead to turbulence in blood flow, resulting in a murmur.

...