'parallelness' originates from English, specifically formed from the adjective 'parallel' plus the suffix '-ness' (a noun-forming suffix meaning 'state or condition').

'parallel' comes into English via Middle French and Latin from Greek 'parallēlos' (παράλληλος), where 'para-' meant 'beside' and 'allēlos' meant 'one another'; the noun-forming '-ness' was later appended in English to create 'parallelness'.

Initially related to the Greek sense of 'lying beside one another', it evolved into the English sense of 'having the property of being side by side or corresponding', and 'parallelness' denotes that state or the analogous quality.