impair

transitive verb | \ im-ˈper \ | im·pair

1. : to damage or make worse by or as if by diminishing impaired health

2. : to diminish the value of (property or property rights); specifically : to diminish the value of (legal contractual obligations) to the point that a party loses the benefit of the contract or the contract otherwise becomes invalid a law impairing a state's own obligations was entitled to less deference —Gerald Gunther — see also contract clause : to diminish the value of (legal contractual obligations) to the point that a party loses the benefit of the contract or the contract otherwise becomes invalid a law impairing a state's own obligations was entitled to less deference —Gerald Gunther — see also contract clause