Legal Definition of Annuity: A yearly payment, usually paid by an insurance company to an insured. The annuity may be for a certain specified number of years or for life | Discover the legal definition of annuity and how it can benefit business owners. Learn how annuities provide financial security, tax advantages, diversification, and legacy planning. Consult with a financial advisor to explore the different types of annuities available for your business and personal goals