aspherical

or a·spher·ic

[ ey-sfer-i-kuh l or ey-sfer-ik ]
/ eɪˈsfɛr ɪ kəl or eɪˈsfɛr ɪk /

adjective Optics.

(of a reflecting surface or lens) deviating slightly from a perfectly spherical shape and relatively free from aberrations.

Origin of aspherical

First recorded in 1920–25; a-6 + spherical
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019