The term "gibbous lune" is introduced in this work for a lune occupying more than half the area of the disk from which it is formed. The terminology is based on the astronomical term gibbous for a Moon phase that appears more than half, but not fully, illuminated.
Gibbous Lune
See also
Crescent, LuneExplore with Wolfram|Alpha
References
Dunham, W. "Hippocrates' Quadrature of the Lune." Ch. 1 in Journey through Genius: The Great Theorems of Mathematics. New York: Wiley, pp. 1-20, 1990.Cite this as:
Weisstein, Eric W. "Gibbous Lune." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/GibbousLune.html