Noun
An uncommon variation of the clover, having four leaves instead of the usual three.
(idiomatic) A bringer of good luck.
Source: en.wiktionary.orgI think of basset hounds whenever I turn on my computer because I have photos of them. And if I'm lucky, and I see one on the street, I know it's going to be a good day. They really are like a four-leaf clover. Julie Klausner
Also in the 1970s and through the 1980s golden four-leaf clover badges were used to denote the most luxurious and well-equipped variants of Alfa Romeo cars, named "Quadrifoglio Oro" or "Gold Cloverleaf". Source: Internet
For example, "the Tornado" takes visitors who sit in the four-leaf clover shaped ring from high up down a huge horn-like cone. Source: Internet
To banish his bad luck, when the Targa Florio came around, the driver painted a white square with a green four-leaf clover (the quadrifoglio) in the centre of the grille of his car. Source: Internet
Your odds of finding a four-leaf clover are 1 in 10,000! Source: Internet