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
Unfortunately for Perseids enthusiasts, the waning gibbous moon will coincide with the maximum activity period of the shower this year.
—
Maia Pandey, jsonline.com, 23 July 2025
That’s how huge impact of a bright gibbous moon is.
—Jamie Carter, Forbes.com, 21 July 2025
This year, a waning gibbous moon three days past full moon phase will seriously hamper the Perseid meteor shower, so why not take this opportunity to try and view the other four, all but one of which will enjoy dark skies?
—Joe Rao, Space.com, 16 July 2025
Saturn will rise above the eastern horizon beneath the stars of the constellation Pisces shortly before midnight for viewers in the U.S. on July 15, with the waning gibbous moon shining roughly three degrees to its upper right.
—Anthony Wood, Space.com, 15 July 2025
See All Example Sentences for gibbous
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Maia Pandey, jsonline.com, 23 July 2025
That’s how huge impact of a bright gibbous moon is.
—Jamie Carter, Forbes.com, 21 July 2025
This year, a waning gibbous moon three days past full moon phase will seriously hamper the Perseid meteor shower, so why not take this opportunity to try and view the other four, all but one of which will enjoy dark skies?
—Joe Rao, Space.com, 16 July 2025
Saturn will rise above the eastern horizon beneath the stars of the constellation Pisces shortly before midnight for viewers in the U.S. on July 15, with the waning gibbous moon shining roughly three degrees to its upper right.
—Anthony Wood, Space.com, 15 July 2025
See All Example Sentences for gibbous
Cite this Entry
“Gibbous.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/gibbous. Accessed 6 Aug. 2025.
Copy CitationKids Definition
Medical Definition
1
: marked by swelling or convexity especially on one side : protuberant
2
: having a hump
Love words? Need even more definitions?
Merriam-Webster unabridged
Share