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

At 11 days old in its lunar cycle, the moon will be in its waxing gibbous phase, with around 92% of its disk illuminated by sunlight. —Samantha Mathewson, Space.com, 10 Jan. 2025

The moon is currently in its waxing gibbous phase at 58% illumination, according to Space.com. —Jenna Prestininzi, Detroit Free Press, 10 Dec. 2024

However, a waning gibbous moon will interfere with Leonid meteors in 2024. —Diana Leyva, The Tennessean, 13 Nov. 2024

The waxing gibbous Moon in your sign creates trines with Saturn, the Sun, and Neptune; squares off against Mercury; and opposes Uranus and Mars. —Jennifer Culp, Them, 12 July 2024

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

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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