The semiminor axis (also called the minor semi-axis, minor semiaxis, or minor radius) of an ellipse (or related figure) is half its extent along the shorter of the two principal axis.
Semiminor Axis
See also
Ellipse, Radius, Semimajor AxisExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Semiminor Axis." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/SemiminorAxis.html