aplanatic
|a-pla-na-tic|
🇺🇸
/ˌeɪpləˈnætɪk/
🇬🇧
/əˈplænətɪk/
free from optical aberration
Etymology
'aplanatic' originates from New Latin 'aplanaticus', ultimately from Greek 'aplanatos', where 'a-' meant 'not' and 'planas' (from 'planasthai') meant 'to stray or wander'.
'aplanatos' (Greek) became New Latin 'aplanaticus' in scientific usage and was adopted into English in the 19th century as 'aplanatic' for optical terminology.
Initially it carried the sense 'not wandering' or 'undeviating'; over time it specialized in scientific contexts to mean 'free from optical aberration' (especially spherical aberration).
Meanings by Part of Speech
Adjective 1
(optics) Free from optical aberrations (especially spherical aberration); producing images without significant distortion due to spherical aberration.
An aplanatic lens is designed to form sharp images by minimizing spherical aberration.
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Adjective 2
(general, rare/archaic) Not deviating; undeviating or unswerving in path or action.
In older texts, aplanatic was occasionally used to describe a straight, undeviating course.
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Last updated: 2025/09/18 09:56