'aquaticity' originates from Latin, specifically the word 'aquaticus', where 'aqua' meant 'water' and the suffix '-ity' comes from Latin '-itas' meaning 'state or condition'.

'aquaticity' developed from the Latin adjective 'aquaticus' (via Late Latin and French forms such as 'aquatique'), which became English 'aquatic' in Middle/Late English; the noun 'aquaticity' was later formed in Modern English by adding the noun-forming suffix '-ity'.

Initially it meant 'pertaining to or connected with water' (as an adjective); over time the derived noun came to mean 'the quality or state of being aquatic'.