What is the meaning of Attrition?

Grinding down or wearing away by friction.

The wearing of teeth due to their grinding.

A gradual reduction in number.

A gradual, natural reduction in membership or personnel, as through injury, incapacitation, retirement, resignation, or death.

The loss of participants during an experiment.

The loss of a first or second language or a portion of that language.

Imperfect contrition or remorse.

To grind or wear down through friction.

To reduce the number of (jobs or workers) by not hiring new employees to fill positions that become vacant (often with out).

To undergo a reduction in number.

attrition

Source: wiktionary.org