A bonanza is a sudden discovery of great wealth or a time of abundant success and good fortune. The word originally described the discovery of a rich vein of gold or silver in a mine. When prospectors during the California Gold Rush hit a bonanza, they struck it rich, finding far more precious metal than they had hoped for.

Today, bonanza describes any windfall or period of unexpected abundance. A farmer might experience a bonanza when perfect weather leads to an exceptionally large harvest. A bookstore has a bonanza when a surprise bestseller flies off the shelves faster than it can restock it. Scientists hit a bonanza when an expedition uncovers far more fossils than expected.

The word carries a sense of excitement and luck, describing extraordinary success that exceeds what anyone anticipated. When your neighbor's lemonade stand becomes wildly popular and sells out in an hour, that's a bonanza. When a fossil hunter finds one dinosaur bone and then discovers an entire skeleton, that's a bonanza too.

People sometimes use bonanza playfully to describe smaller good fortunes, like finding a bonanza of Halloween candy after trick-or-treating, or discovering a bonanza of interesting shells on the beach.