Wiktionary
n. 1 An affluent individual who provides capital for a business start-up, usually in exchange for convertible debt or ownership equity. 2 A rainmaker.
Wikipedia
An angel investor or angel (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.
Usage examples of "angel investor".
MacDiarmid hustled away to join the rest of the investors, his exquisite handmade leather shoes slapping the paving, the cuffs of his wool tailor-made slacks shushing over their gleaming uppers, and as Lee-Daniel locked the bus down and armed it up, he watched the angel investor whisper in his co-shareholders' ears.