'nonaqueousness' is a Modern English formation combining the prefix 'non-' (meaning 'not'), the adjective 'aqueous' (meaning 'of water'), and the suffix '-ness' (forming a noun indicating a state or quality).

'aqueous' originates from Latin 'aqua' meaning 'water' (via Late Latin forms such as 'aquāeus'); the negative prefix 'non-' comes from Latin 'non'. These elements were combined in English to form 'nonaqueous' and later the noun-forming '-ness' produced 'nonaqueousness'.

Originally 'aqueous' meant 'of or relating to water' (from Latin 'aqua'); the compound 'nonaqueousness' specifically denotes the absence of water and has been used in technical contexts (especially chemistry) to describe non-water-based media.