Immunization is a risk mitigation strategy that equalizes the duration of assets and liabilities so that the value of the portfolio is protected from changes in interest rates.
Impairment may occur as a result of an unusual or one-time event, such as a change in legal or economic conditions, a change in customer demand, or damage to an asset.
Impeachment, as defined in Article II, Section 4 of the US Constitution, is a formal procedure whereby Congress brings charges against high-ranking civil servants, such as the president, in an attempt to remove them from office.