Gibbous is most often used to describe the moon or a planet when it is seen with more than half but not all of the apparent disk illuminated.

// The waxing gibbous moon provided the perfect lighting for a night of spooky storytelling around the campfire.

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“At 3:30 a.m. the gibbous moon is high in the south and Perseus is nearly overhead. Set up a comfortable lawn chair facing away from any bright lights, ideally looking toward the northeast with the moon to your back. Have insect repellent handy along with hot chocolate, tea or coffee and enjoy the show.” — Tim Hunter, The Arizona Daily Star, 7 Aug. 2025

The adjective gibbous has its origins in the Latin noun gibbus, meaning “hump.” It was adopted into Middle English to describe rounded, convex things. While it has been used to describe the rounded body parts of humans and animals (such as the back of a camel) and to describe the shape of certain flowers (such as snapdragons), the term is most often used to describe the moon: a gibbous moon is one that is between half full and full.