'aquatile' originates from Latin, specifically the word 'aquatilis', where 'aqua' meant 'water' and the suffix '-tilis/-ilis' indicated 'pertaining to'.

'aquatilis' was used in Latin (and Medieval/Neo-Latin) to mean 'of or belonging to water' and was later borrowed into English as 'aquatile' (a rare/archaic adjective) through scholarly/technical usage.

Initially it meant 'pertaining to water' in Latin and this core meaning has largely remained the same in English, though the word is less common than the variant 'aquatic'.