'aplanatism' originates from modern scientific formation based on the adjective 'aplanatic' (from New Latin/Modern French usage), where the element 'a-' meant 'not' and the root related to Greek 'planēs'/'planasthai' (to wander) or 'planos' (wandering), yielding the sense 'not wandering' (i.e., not deviating).

'aplanatism' developed from the adjective 'aplanatic' (recorded in 19th-century optical literature), which itself came into scientific use via New Latin and French 'aplanatique'/'aplanatisme'; these in turn trace back to Greek components used in classical and Hellenistic scientific vocabulary.

Initially constructed to convey the literal sense 'not wandering' (no deviation), the term evolved in technical optics to mean specifically 'free from or corrected for certain image-degrading deviations (aberrations)', and now denotes that optical quality.