Attrition

[əˈtrɪʃ(ə)n]
Definition:

Attrition refers to the number of employees that have left the organization over time; this could have been through voluntary and involuntary, whose positions are not refilled.

Part of speech:
noun
Synonyms:
wearing down
wearing away
weakening
debilitation
enfeebling
sapping
attenuation
Use in a sentence:
The council is trying to wear down the opposition by attrition
Attrition