1. a group of stars that form a recognizable pattern or shape in the night sky, smaller or less formally defined than a constellation
Usage: astronomy; common in casual stargazing
2. a star-shaped optical effect seen in certain gemstones when light reflects off their surface
Usage: gemology; technical

Examples

• The Big Dipper is a famous asterism within the larger constellation Ursa Major.
• Many people recognize the asterism of Orion's Belt in the winter sky.
• The Summer Triangle is an asterism formed by three bright stars: Vega, Altair, and Deneb.
• A ruby with a strong asterism displays a beautiful star pattern when polished.
• Gemologists value sapphires that show a clear asterism effect.
• Unlike constellations, an asterism does not have official boundaries set by astronomers.
• The asterism known as the Teapot is visible in the constellation Sagittarius.