'astigmometer' originates from a modern medical coinage using Greek elements: specifically the Greek prefix 'a-' (not) + 'stigma' (point, mark) forming 'astigmat-' (as in 'astigmatism'), combined with Greek 'metron' (measure) via the suffix '-meter'.

'astigmometer' was formed in English by combining the stem from 'astigmatism' (itself from Greek elements) with the suffix '-meter' to name devices that measure astigmatism; it entered medical/optical usage as the technical name for such instruments.

Initially it meant 'an instrument for measuring astigmatism,' and this specific technical meaning has remained consistent in ophthalmic and optometric contexts.