gib·​bous ˈji-bəs How to pronounce gibbous (audio) ˈgi- How to pronounce gibbous (audio)
: marked by convexity or swelling
of the moon or a planet : seen with more than half but not all of the apparent disk illuminated
: 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 However, the full moon will fall on October 17, which means a waning gibbous moon will compete with the shower at its peak. Margaret Osborne, Smithsonian Magazine, 2 Jan. 2024 On December 21 and 22 nights, a waxing gibbous moon will drop by Jupiter. Jamie Carter, Forbes, 30 Nov. 2023 While finding a dark location is preferred, there's not much us Earthlings can due to combat the glaring waning gibbous moon — so instead of spotting 100 to 150 meteors per hour, viewers in the Northern Hemisphere are more likely to catch 30 to 40 instead. Skyler Caruso, Peoplemag, 29 Nov. 2023 For example, a waning crescent will form a full moon with a waxing gibbous, first-quarter moons and third-quarter moons will come together as a perfect whole, and so on. Aliza Pelto, Women's Health, 10 Sep. 2023 Waxing gibbous The waxing gibbous is when the results of your manifestation endeavors will begin to appear. Aliza Pelto, Women's Health, 17 Mar. 2023 The gibbous moon illuminates the trees. Rebecca Curtis, The New Yorker, 9 Nov. 2020 To note, from Thursday night into Friday morning, NASA said the bright star Spica will appear near the waning gibbous moon. Julia Musto, Fox News, 8 Mar. 2023 Last year’s waning gibbous moon resulted in only about 30 to 40 visible meteors per hour in the Northern Hemisphere. Margaret Osborne, Smithsonian Magazine, 30 Jan. 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'gibbous.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


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

First Known Use

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

Time Traveler
The first known use of gibbous was in the 14th century


Dictionary Entries Near gibbous

Cite this Entry

“Gibbous.” Dictionary, Merriam-Webster, Accessed 2 Mar. 2024.

Kids Definition


gib·​bous ˈjib-əs How to pronounce gibbous (audio) ˈgib- How to pronounce gibbous (audio)
: seen with more than half but not all of the disk lighted
gibbous moon

Medical Definition


gib·​bous ˈjib-əs How to pronounce gibbous (audio) ˈgib- How to pronounce gibbous (audio)
: marked by swelling or convexity especially on one side : protuberant
: having a hump
Last Updated: - Updated example sentences
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