'asiatical' originates from Latin, specifically the word 'asiaticus', where 'asiaticus' meant 'of Asia' (from Greek 'Asiatikos' from 'Asia').

'asiatical' came into English via Late Latin/Medieval Latin forms such as 'asiaticus' and through usage in Early Modern English; the element ultimately traces back to Greek 'Asiatikos' derived from the place-name 'Asia'.

Initially, it meant 'of or relating to Asia' and over time has remained similar in meaning but grown rare/archaic in modern English, largely replaced by 'Asiatic' or 'Asian'.