The Merriam-Webster Word of the Day is gibbous. Read on for what it means, how it’s used, and more.

What It Means

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

// The lake’s calm surface glistened under the light of the waxing gibbous moon.

GIBBOUS in Context

“Eventually, we lay our heads down on our pillows beneath a clear sky (no tent required) and a bright gibbous moon that left the canyon well illuminated. I never even unpacked a flashlight.” — David Courtney, Texas Monthly, July 2022

Did You Know?

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.