What does gibbousness mean?
Gibbousness is the noun for the quality of being gibbous: rounded, convex, or bulging outward. The word can describe any swollen or outward-curving form, but it is particularly familiar in astronomy. A gibbous Moon appears more than half illuminated while remaining short of full, occurring in both waxing and waning phases. The term often gives descriptions a visual or literary emphasis, as in references to the gibbousness of a planet, a sculpture, or the Moon. It is more formal and less everyday than gibbous, and in general contexts convexity or bulge may be more natural. Nevertheless, gibbousness usefully names the condition itself rather than merely labeling an object with an adjective, making it valuable in precise descriptions of shape, appearance, and lunar cycles.
nounThe state or quality of being gibbous, especially of having a rounded, convex or bulging form. In astronomy, it refers to the condition of the Moon when more than half, but less than all, of its visible disc is illuminated.
- The state or quality of being gibbous; a rounded, convex or bulging condition, especially the illuminated phase of the Moon between half-moon and full moon.
"The gibbousness of the rising moon was softened by the mist."
"The sculptor emphasized the gibbousness of the stone with broad, swelling curves."
"As the Moon waxes toward full, its gibbousness becomes increasingly apparent."
The plural is grammatically possible but rarely used.
"The chart distinguishes the waxing and waning gibbousnesses of the lunar cycle."
A gibbous moon shows more than half its face, but not the whole face: a shyly luminous shape between half-moon and full moon.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of gibbousness
Gibbousness derives from the English adjective gibbous, which comes through French from Latin gibbosus, meaning hump-backed or bulging. The Latin adjective was formed from gibbus, a word associated with a hump or swelling. English then added the suffix -ness to gibbous to form the noun expressing the state or quality of being gibbous.
Related word forms
How gibbousness is actually used
Formal and somewhat literary. It is less common than the adjective gibbous and is especially associated with descriptions of rounded forms and lunar phases.
Easily confused with gibbousness
Gibbousness is the noun for the quality of being rounded or bulging, while gibbous is the adjective describing such a form.