Attrition (noun)

1. The process of reducing something's strength or effectiveness through sustained attack or pressure.
2. The gradual reduction in the number of employees through retirement or resignation.

Origin:

Late 16th century: from latin attritio(n-), from atterere "to rub against", from ad- "to" + terere "to rub".

Examples:

1. The company experienced a high rate of attrition in the sales department.
2. The battle resulted in heavy attrition on both sides.
3. Attrition of the workforce is a major concern.
4. The company's profits were affected by the attrition of customers.
5. The team suffered from attrition due to injuries.