gibbous

adjective

gib·​bous ˈji-bəs  ˈgi- 

1

a

: marked by convexity or swelling

b

of the moon or a planet : seen with more than half but not all of the apparent disk illuminated

2

: having a hump : humpbacked

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.

Examples of gibbous in a Sentence

Recent Examples on the Web

When And Where To Look After sunset, look to the eastern horizon to spot the 97%-illuminated waning gibbous moon rising with Saturn close by. —Jamie Carter, Forbes.com, 7 Sep. 2025

Sadly, the light of a waning gibbous moon washed out all but the brightest shooting stars this year, though photographers were still able to capture stunning compositions featuring the most brilliant members of the annual shower. —Anthony Wood, Space.com, 3 Sep. 2025

So whether your lunar calendar reads a full moon or waning gibbous, a Strawberry Moon or Sturgeon Moon, the moon isn’t the likely culprit behind your kids’ trouble sleeping. —Taylor Grothe, Parents, 27 Aug. 2025

The waxing gibbous moon rises in the middle of the afternoon and sets around 2 or 3 in the morning. —Mike Lynch, Twin Cities, 24 Aug. 2025

Word History

Etymology

Middle English, from Late Latin gibbosus humpbacked, from Latin gibbus hump

First Known Use

14th century, in the meaning defined at sense 1a

Kids Definition

gibbous

adjective

gib·​bous ˈjib-əs  ˈgib- 

: seen with more than half but not all of the disk lighted

gibbous moon

Medical Definition

gibbous

adjective

gib·​bous ˈjib-əs  ˈgib- 

1

: marked by swelling or convexity especially on one side : protuberant

2

: having a hump