'aquilian' originates from Latin, specifically from the title 'Lex Aquilia' or the family name 'Aquilius', where 'Aquilia' referred to the law associated with that family (the statute addressing wrongful damage).

'aquilian' developed from Medieval/Legal Latin usages such as 'aquilianus' (pertaining to the Aquilia), passed into legal English to describe actions or principles derived from the Lex Aquilia.

Initially it referred specifically to the Roman statute 'Lex Aquilia' or matters directly arising under that statute; over time it has been used more generally in legal contexts to mean 'relating to claims for damages' or 'tortious'.