GIBBOUS Definition & Meaning | Dictionary.com (original) (raw)

[gib-_uh_s] / ˈgɪb əs /

Also gibbose

adjective

Astronomy. (of a heavenly body) convex at both edges, as the moon when more than half full.
humpbacked.

gibbous British

/ ˈɡɪbəʊs, ˈɡɪbəs /

adjective

(of the moon or a planet) more than half but less than fully illuminated
having a hunchback; hunchbacked
bulging

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

gibbous Scientific

/ gĭb′əs /

More than half but less than fully illuminated. Used to describe the Moon or a planet.
Compare crescent

Other Word Forms

Etymology

Origin of gibbous

1350–1400; Middle English < Latin gibbōsus humped, equivalent to gibb ( a ) hump + -ōsus -ous

Explanation

Gibbous describes a certain phase of the moon, when it's bulging outward but isn't quite full. A waxing gibbous moon is one that's getting progressively rounder, night after night. Occasionally the adjective gibbous is used for describing something else that protrudes or bulges, like a sleepy kitten's gibbous belly. Usually, though, it's used for the moon. When the moon isn't new (invisible from the earth) or full, it's either crescent or gibbous. Whenever the moon appears larger than a semicircle, but not quite a circle, you can describe it as gibbous.

Keep Reading on Vocabulary.com

Vocabulary lists containing gibbous

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

“The waning gibbous moon will severely compromise this shower at the time of maximum activity,” notes the American Meteor Society.

FromLos Angeles Times • Jul. 29, 2025

The Moon will be in a waxing gibbous phase – going from half moon to full moon.

FromBBC • Nov. 9, 2024

Even now, however, a waning gibbous moon will still somewhat impede viewing conditions.

FromSalon • Oct. 18, 2024

The waxing gibbous moon will set around midnight, ushering in excellent viewing conditions later in the night and predawn hours.

FromNational Geographic • Dec. 6, 2023

His friend who owns the motorcar set off at top speed, full out and going like the clappers, no lights as usual except the waning gibbous moon on the rise.

From"Code Name Verity" by Elizabeth Wein

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023