'aspherical' originates from Modern English, formed by the privative prefix 'a-' (meaning 'not') attached to 'spherical', which ultimately derives from Greek 'sphaira' meaning 'ball'.

'spherical' entered English via Latin (e.g. 'sphaericus') and Old French, ultimately from Greek 'sphaira'; 'aspherical' was created in Modern English by adding the prefix 'a-' to 'spherical'.

Initially, 'spherical' meant 'relating to a sphere'; by adding the privative 'a-' the compound came to mean 'not spherical', a sense especially used in technical contexts (surfaces, optics).