A tax deferred pension plan available to self-employed individuals or unincorporated businesses for retirement purposes. A Keogh plan can be set up as either a defined-benefit or defined-contribution plan, although most plans are defined contribution.
Also known as an HR(10) plan, Keogh plans can invest in the same set of securities as 401(k)s and IRAs, including stocks, bonds, certificates of deposit and annuities.
Explained further: Contributions are generally tax deductible up to 25% of annual income with a limit of $47,000 (as of 2007). Keogh plan types include money-purchase plans (used by high-income earners), defined-benefit plans (which have high annual minimums) and profit-sharing plans (which offer annual flexibility based on profits).
Definition courtesy of Investopedia