mitigation of damages

Definition from Nolo’s Plain-English Law Dictionary

The requirement that someone injured by another's negligence or breach of contract must take reasonable steps to reduce the damages, injury, or cost, and to prevent them from getting worse. If a tenant breaks a lease and moves out without legal justification, a landlord must try to rerent the property reasonably quickly and keep his or losses to a minimum -- that, is to mitigate damages. In another context, a person claiming to have been injured by another motorist should seek medical help and not let the problem worsen.

Definition provided by Nolo’s Plain-English Law Dictionary.