Noun
angel investor (plural angel investors)
(business) An investor to a start-up, especially one who invests very early or during the company's initial forming.
Synonyms: business angel, angel
The best part of being an angel investor is seeing these kids coming up with companies that get way more traffic than Reddit had when we sold it. I think, 'Are you kidding me? They're just kids, and they've done so much.' Alexis Ohanian
As startup mentor and Angel investor Martin Zwilling, "If your friends and family don’t believe in you, don’t expect outsiders to jump in." Source: Internet