You searched for: “asphere
asphere (s) (noun), aspheres (pl)
A lens whose surfaces have a profile that is neither a portion of a sphere nor of a circular cylinder: "The asphere's more complex surface profile can reduce or eliminate spherical aberration and also reduce other optical aberrations compared to a simple lens because a single asphere type of lens can often replace a much more complex multi-lens system.

—As seen in
"Ophthalmic Lens Design",
This entry is located in the following unit: sphero-, spher-, -sphere- (page 1)