'off-axis' originates from English, combining the adverb 'off' and the noun 'axis', where 'off' meant 'away from' and 'axis' meant 'axis' or 'axle' (from Latin).

'off' comes from Old English 'of' meaning 'away, away from'; 'axis' comes from Latin 'axis' (axis, axle) and entered English via scientific/Latin usage. The compound 'off-axis' is a modern technical formation (20th century) used in engineering and optics.

Initially the components meant 'away' and 'axis'; combined as 'off-axis' it evolved into a specific technical adjective/adverb meaning 'away from the central axis' used especially in scientific and engineering contexts.