What is Angel Investor?

Legal Definition
An angel investor (also known as a business angel, informal investor, angel funder, private investor, or seed investor) is an affluent individual who provides capital for a business start-up, usually in exchange for convertible debt or ownership equity. A small but increasing number of angel investors invest online through equity crowdfunding or organize themselves into angel groups or angel networks to share research and pool their investment capital, as well as to provide advice to their portfolio companies.
-- Wikipedia
Legal Definition
A former business owner that gives starting money for new ventures. They also advise and provide contacts. They act alone and work indirectly with the operations. AKA business angel.