An act of legislation that makes a large number of reforms to U.S. pension plan laws and regulations. This law made several pension provisions from the Economic Growth and Tax Relief Reconciliation Act of 2001 permanent, including the increased IRA contribution limits and the increased salary deferral contribution limits to a 401(k). It also attempts to strengthen the overall pension system and reduce the reliance on the federal pension system and the Pension Benefit Guaranty Corporation.
Explained further: Along with making past provisions permanent, the act also attempts to strengthen the pension system. This is done through the requirement that companies with under-funded pensions pay additional premiums along with the elimination of loopholes that allowed under-funded pensions to miss pension payments. The act also requires that pension plans provide more accurate assessments of their pension obligations.
Definition courtesy of Investopedia